„In the great body of human society it is impossible to establish unity and coordination if one part is considered perfect and the other imperfect. When the perfect functions of both parts are in operation, harmony will prevail.“

„No one is perfect in this imperfect world.“

—  Patrice Lumumba Congolese Prime Minister, cold war leader, executed 1925 - 1961

Congo, My Country

„To love truth for truth's sake is the principal part of human perfection in this world, and the seed-plot of all other virtues.“

—  John Locke English philosopher and physician 1632 - 1704

Letter to Anthony Collins (29 October 1703) http://oll.libertyfund.org/titles/1726#lf0128-09_head_098

„The universe is not required to be in perfect harmony with human ambition.“

—  Carl Sagan American astrophysicist, cosmologist, author and science educator 1934 - 1996

„I have never claimed that democracy was a perfect system because we human beings are not perfect. We are not capable of producing a system that is perfect. But I think there is something nice and challenging about imperfection. If we were all perfect I think it would be a very boring world. But as it is because we have to cope everyday with our imperfections everyday can become a day of excitement. You wake up and say to yourself now which one of my many imperfections shall I work on today and that makes it very interesting and very challenging. But it is more important that we work on the imperfections of societies and of laws and of practices that truly hurt us as human beings, that erode the foundation of human dignity.“

—  Aung San Suu Kyi State Counsellor of Myanmar and Leader of the National League for Democracy 1945

Sakharov Prize for Freedom of Thought Acceptance Speech (2013)

„It is because human needs are contradictory that no human life can be perfect. That does not mean that human life is imperfect. It means that the idea of perfection has no meaning.“

—  John Gray British philosopher 1948

'Modus Vivendi' (p.29)
Gray's Anatomy: Selected Writings (2009)

„To accomplish the perfect perfection, a little imperfection helps.“

—  Dejan Stojanovic poet, writer, and businessman 1959

Imperfection http://www.poetrysoup.com/famous/poem/21399/Imperfection
From the poems written in English

„I cannot without great astonishment — I might say without great insult to my intelligence — hear it attributed as a prime perfection and nobility of the natural and integral bodies of the universe that they are invariant, immutable, inalterable, etc., while on the other hand it is called a great imperfection to be alterable, generable, mutable, etc. For my part I consider the earth very noble and admirable precisely because of the diverse alterations, changes, generations, etc. that occur in it incessantly. If, not being subject to any changes,“

—  Galileo Galilei, libro Dialogue Concerning the Two Chief World Systems

Sagredo
Variant translation: I cannot without great wonder, nay more, disbelief, hear it being attributed to natural bodies as a great honor and perfection that they are impassable, immutable, inalterable, etc.: as conversely, I hear it esteemed a great imperfection to be alterable, generable, and mutable. It is my opinion that the earth is very noble and admirable by reason of the many and different alterations, mutations, and generations which incessantly occur in it. And if, without being subject to any alteration, it had been one great heap of sand, or a mass of jade, or if, since the time of the deluge, the waters freezing which covered it, it had continued an immense globe of crystal, wherein nothing had ever grown, altered, or changed, I should have esteemed it a wretched lump of no benefit to the Universe, a mass of idleness, and in a word superfluous, exactly as if it had never been in Nature. The difference for me would be the same as between a living and a dead creature. I say the same concerning the Moon, Jupiter, and all the other globes of the Universe.
The more I delve into the consideration of the vanity of popular discourses, the more empty and simple I find them. What greater folly can be imagined than to call gems, silver, and gold noble, and earth and dirt base? For do not these persons consider that if there were as great a scarcity of earth as there is of jewels and precious metals, there would be no king who would not gladly give a heap of diamonds and rubies and many ingots of gold to purchase only so much earth as would suffice to plant a jessamine in a little pot or to set a tangerine in it, that he might see it sprout, grow up, and bring forth such goodly leaves, fragrant flowers, and delicate fruit? It is scarcity and plenty that makes things esteemed and despised by the vulgar, who will say that there is a most beautiful diamond, for it resembles a clear water, and yet would not part from it for ten tons of water. 'These men who so extol incorruptibility, inalterability, and so on, speak thus, I believe, out of the great desire they have to live long and for fear of death, not considering that, if men had been immortal, they would not have come into the world. These people deserve to meet with a Medusa's head that would transform them into statues of diamond and jade, that so they might become more perfect than they are.
Part of this passage, in Italian, I detrattori della corruptibilitá meriterebber d'esser cangiati in statue., has also ben translated into English as "Detractors of corruptibility deserve being turned into statues."
Dialogo sopra i due massimi sistemi del mondo. (PDF) http://www.liberliber.it/biblioteca/g/galilei/le_opere_di_galileo_galilei_edizione_nazionale_sotto_gli_etc/pdf/le_ope_p.pdf, Le Opere di Galileo Galilei vol. VII, pg. 58.
Compare Maimonides "If man were never subject to change there could be no generation; there would be one single being..." Guide for the Perplexed (c. 1190)
Dialogue Concerning the Two Chief World Systems (1632)
Contexto: I cannot without great astonishment — I might say without great insult to my intelligence — hear it attributed as a prime perfection and nobility of the natural and integral bodies of the universe that they are invariant, immutable, inalterable, etc., while on the other hand it is called a great imperfection to be alterable, generable, mutable, etc. For my part I consider the earth very noble and admirable precisely because of the diverse alterations, changes, generations, etc. that occur in it incessantly. If, not being subject to any changes, it were a vast desert of sand or a mountain of jasper, or if at the time of the flood the waters which covered it had frozen, and it had remained an enormous globe of ice where nothing was ever born or ever altered or changed, I should deem it a useless lump in the universe, devoid of activity and, in a word, superfluous and essentially non-existent. This is exactly the difference between a living animal and a dead one; and I say the same of the moon, of Jupiter, and of all other world globes.
The deeper I go in considering the vanities of popular reasoning, the lighter and more foolish I find them. What greater stupidity can be imagined than that of calling jewels, silver, and gold "precious," and earth and soil "base"? People who do this ought to remember that if there were as great a scarcity of soil as of jewels or precious metals, there would not be a prince who would not spend a bushel of diamonds and rubies and a cartload of gold just to have enough earth to plant a jasmine in a little pot, or to sow an orange seed and watch it sprout, grow, and produce its handsome leaves, its fragrant flowers, and fine fruit. It is scarcity and plenty that make the vulgar take things to be precious or worthless; they call a diamond very beautiful because it is like pure water, and then would not exchange one for ten barrels of water. Those who so greatly exalt incorruptibility, inalterability, etc. are reduced to talking this way, I believe, by their great desire to go on living, and by the terror they have of death. They do not reflect that if men were immortal, they themselves would never have come into the world. Such men really deserve to encounter a Medusa's head which would transmute them into statues of jasper or of diamond, and thus make them more perfect than they are.

„Let the states of equilibrium and harmony exist in perfection, and a happy order will prevail throughout heaven and earth, and all things will be nourished and flourish.“

—  Confucius Chinese teacher, editor, politician, and philosopher -551 - -479 a.C.

Fuente: The Doctrine of the Mean

„Marriage is two imperfect people committing themselves to a perfect institution, by making perfect vows from imperfect lips before a perfect God.“

—  Myles Munroe Bahamian Evangelical Christian minister 1954 - 2014

Fuente: The Purpose and Power of Love & Marriage

„Since no one is perfect, it follows that all great deeds have been accomplished out of imperfection.“

—  Lois McMaster Bujold, libro Mirror Dance

Fuente: Vorkosigan Saga, Mirror Dance (1994)

„There is something perfect to be found in the imperfect: the law keeps balance through the juxtaposition of beauty, which gains perfection through nurtured imperfection.“

—  Dejan Stojanovic poet, writer, and businessman 1959

Mastery http://www.poemhunter.com/poem/mastery-2/
From the poems written in English

„I say, life and figure are distinct attributes of one substance, and as one and the same body may be transmuted into all kinds of figures; and as the perfecter figure comprehends that which is more imperfect; so one and the same body may be transmuted from one degree of life to another more perfect, which always comprehends in it the inferior.“

—  Anne Conway British philosopher 1631 - 1679

The Principles of the Most Ancient and Modern Philosophy (1690)
Contexto: I say, life and figure are distinct attributes of one substance, and as one and the same body may be transmuted into all kinds of figures; and as the perfecter figure comprehends that which is more imperfect; so one and the same body may be transmuted from one degree of life to another more perfect, which always comprehends in it the inferior. We have an example of figure in a triangular prism, which is the first figure of all right lined solid triangular prism, which is the first figure of all right lined solid bodies, where into a body is convertible; and from this into a cube, which is a perfecter figure, and comprehends in it a prism; from a cube it may be turned into a more perfect figure, which comes nearer to a globe, and from this into another, which is yet nearer; and so it ascends from one figure, more imperfect to another more perfect, ad infinitum; for here are no bounds; nor can it be said, this body cannot be changed into a perfecter figure: But the meaning is that that body consists of plane right lines; and this is always chageablee into a perfecter figure, and yet can never reach to the perfection of a globe, although it always approaches nearer unto it; the case is the same in diverse degrees of life, which have indeed a beginning, but no end; so that the creature is always capable of a farther and perfecter degree of life, ad infinitum, and yet can never attain to be equal with God; for he is still infinitely more perfect than a creature, in its highest elevation or perfection, even as a globe is the most perfect of all other figures, unto which none can approach.

„Perfection is graciously dealing with imperfection.“

—  David Allen American productivity consultant and author 1945

4 November 2010 https://twitter.com/gtdguy/status/29641324869
Official Twitter profile (@gtdguy) https://twitter.com/gtdguy

„We are perfect in our imperfection.“

—  Megan McCafferty American novelist 1973

Fuente: Second Helpings

„Perfection itself is imperfection.“

—  Vladimir Horowitz American classical pianist and composer 1903 - 1989

Mentioned in Brainy Quotes

„It is only imperfection that complains of what is imperfect. The more perfect we are the more gentle and quiet we become towards the defects of others.“

—  Joseph Addison politician, writer and playwright 1672 - 1719

François Fénelon, in Selections from the Writings of Fenelon: With an appendix, containing a Memoir of his Life (1829) as translated by A Lady (Eliza Lee Cabot Follen) http://books.google.com/books?id=qJ4rAAAAYAAJ, Letter 37, p. 189.
Misattributed

„Nothing we see or hear is perfect. But right there in the imperfection is perfect reality.“

—  Shunryu Suzuki Japanese Buddhist missionary 1904 - 1971

Wherever You Are, Enlightenment Is There (page127)
Not Always So, practicing the true spirit of Zen (2002)

„Unity…. Unity of purpose is shown by continuity, or the proper relationship of the parts with each other, and with the whole as one sees it best expressed in the human form. Unity of mass is obtained by giving predominance of mass to some one feature…“

—  Ernest Flagg American architect 1857 - 1947

Small Houses: Their Economic Design and Construction (1922)

„We adore perfection because we can't have it; it would disgust us if we had it. Perfect is inhuman, because human is imperfect.“

—  Fernando Pessoa, libro Libro del desasosiego

Ibid., p. 249
Original: Adoramos a perfeição, porque não a podemos ter; repugná-la-íamos, se a tivéssemos. O perfeito é o desumano, porque o humano é imperfeito.
Fuente: The Book of Disquiet