Aristotle (384 BC – 7 March 322 BC) was a Greek philosopher and a scientist.

All human actions have one or more of these seven causes:

1. - chance
2. - nature
3. - compulsion
4. - habit
5. - reason
6. - passion
7. - desire

Economics:

"For well-being and health, again, the homestead should be airy in summer, and sunny in winter. A homestead possessing these qualities would be longer than it is deep; and its main front would face the south".

Economics (Oeconomica) 1345a.20, Greek Texts and Translations, Perseus under PhiloLogic.

He who has overcome his fears will truly be free.

Variant: I count him braver who overcomes his desires than him who overcomes his enemies.

Quoted in Florilegium by Joannes Stobaeus

In all things of nature there is something of the marvelous.

Parts of Animals I.645a16

We should venture on the study of every kind of animal without distaste; for each and all will reveal to us something natural and something beautiful.

Parts of Animals I.645a21

Nature flies from the infinite, for the infinite is unending or imperfect, and Nature ever seeks amend.

Generation of Animals I.715b15

Concerning the generation of animals akin to them, as hornets and wasps, the facts in all cases are similar to a certain extent, but are devoid of the extraordinary features which characterize bees; this we should expect, for they have nothing divine about them as the bees have.

Generation of Animals III.761a2

Just as it sometimes happens that deformed offspring are produced by deformed parents, and sometimes not, so the offspring produced by a female are sometimes female, sometimes not, but male, because the female is as it were a deformed male.

Generation of Animals as translated by Arthur Leslie Peck (1943), p. 175

Misfortune shows those who are not really friends.

- Eudemian Ethics VII.1238a20

Time crumbles things; everything grows old under the power of Time and is forgotten through the lapse of Time.

- Physics

Metaphysics

All men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves; and above all others the sense of sight. For not only with a view to action, but even when we are not going to do anything, we prefer sight to almost everything else. The reason is that this, most of all the senses, makes us know and brings to light many differences between things. (I.980a21)

Variant: All men by nature desire knowledge...

The first sentence is in the Oxford Dictionary of Scientific Quotations (2005), 21:10.

If, then, God is always in that good state in which we sometimes are, this compels our wonder; and if in a better this compels it yet more. And God is in a better state. And life also belongs to God; for the actuality of thought is life, and God is that actuality; and God's self-dependent actuality is life most good and eternal. (XII.1072b24)

Those who assert that the mathematical sciences say nothing of the beautiful or the good are in error. For these sciences say and prove a great deal about them; if they do not expressly mention them, but prove attributes which are their results or definitions, it is not true that they tell us nothing about them. The chief forms of beauty are order and symmetry and definiteness, which the mathematical sciences demonstrate in a special degree. (XIII.1078a33)

The single harmony produced by all the heavenly bodies singing and dancing together springs from one source and ends by achieving one purpose, and has rightly bestowed the name not of "disordered" but of "ordered universe" upon the whole. (399 a DE MUNDO)

Lives of Eminent Philosophers

Assertions attributed to Aristotle in Lives of Eminent Philosophers by Diogenes Laërtius

Education is the best provision for old age.

Hope is a waking dream.

I have gained this by philosophy: that I do without being commanded what others do only from fear of the law.

Liars when they speak the truth are not believed.

To the query, "What is a friend?" his reply was "A single soul dwelling in two bodies."

Variants: Friendship is a single soul dwelling in two bodies.

A true friend is one soul in two bodies.

Love is composed of a single soul inhabiting two bodies.

What is a friend? A single soul dwelling in two bodies.

To the query, in the same text, "what is love?" he replied "What is life without love? Love is like the sun; without light, there's no life"

Often repeated:

We are what we repeatedly do, excellence is therefore, not an act, but a habit.

Misattributed:

We are what we repeatedly do. Excellence, then, is not an act, but a habit.

Variant: We are what we repeatedly do, therefore excellence is not an act, but a habit.

Source: Will Durant, The Story of Philosophy: The Lives and Opinions of the World's Greatest Philosophers (1926) [Simon & Schuster/Pocket Books, 1991, ISBN 0-671-73916-6] Ch. II:

Aristotle and Greek Science; part VII: Ethics and the Nature of Happiness:

"Excellence is an art won by training and habituation: we do not act rightly because we have virtue or excellence, but we rather have these because we have acted rightly; 'these virtues are formed in man by his doing the actions'; we are what we repeatedly do.

Excellence, then, is not an act but a habit: 'the good of man is a working of the soul in the way of excellence in a complete life... for as it is not one swallow or one fine day that makes a spring, so it is not one day or a short time that makes a man blessed and happy'" (p. 76).

The quoted phrases within the quotation are from the Nicomachean Ethics, Book II, 4; Book I, 7.

The misattribution is from taking Durant's summation of Aristotle's ideas as being the words of Aristotle himself.

"We live in deeds, not years: In thoughts not breaths; In feelings, not in figures on a dial. We should count time by heart throbs. He most lives Who thinks most, feels the noblest, acts the best."

This is actually from the poem "We live in deeds..." by Philip James Bailey. This explains the strange pattern of capitalization.

The worst form of inequality is to try to make unequal things equal.

This first appears in 1974 in an explanation of Aristotle's politics in Time magazine, before being condensed to an epigram as "Aristotle's Axiom" in Peter's People (1979) by Laurence J. Peter.