“If every instrument could accomplish its own work, obeying or anticipating the will of others, like the statues of Daedalus, or the tripods of Hephaestus, which, says the poet, ‘of their own accord entered the assembly of the Gods’; if, in like manner, the shuttle would weave and the plectrum touch the lyre without a hand to guide them, chief workmen would not want servants, nor masters slaves.”
Book I, part 4 (1920 translation by Benjamin Jowett)
Popularly simplified to when the looms spin by themselves, we'll have no need for slaves.
Politics
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Aristotle 230
Classical Greek philosopher, student of Plato and founder o… -384–-321 BCRelated quotes

Source: The Life of Pasteur (1902), p. 19

Section 4 : Moral Ideals
Founding Address (1876), Life and Destiny (1913)

“Make me thy lyre, even as the forest is:
What if my leaves are falling like its own!”
St. V
Ode to the West Wind (1819)
Context: Make me thy lyre, even as the forest is:
What if my leaves are falling like its own!
The tumult of thy mighty harmonies
Will take from both a deep, autumnal tone,
Sweet though in sadness. Be thou, Spirit fierce,
My spirit! Be thou me, impetuous one!

Letter 56 (60), to Hugo Boxel (1674) http://oll.libertyfund.org/?option=com_staticxt&staticfile=show.php%3Ftitle=1711&chapter=144218&layout=html&Itemid=27
Context: When you say that if I deny, that the operations of seeing, hearing, attending, wishing, &c., can be ascribed to God, or that they exist in him in any eminent fashion, you do not know what sort of God mine is; I suspect that you believe there is no greater perfection than such as can be explained by the aforesaid attributes. I am not astonished; for I believe that, if a triangle could speak, it would say, in like manner, that God is eminently triangular, while a circle would say that the divine nature is eminently circular. Thus each would ascribe to God its own attributes, would assume itself to be like God, and look on everything else as ill-shaped.
The briefness of a letter and want of time do not allow me to enter into my opinion on the divine nature, or the questions you have propounded. Besides, suggesting difficulties is not the same as producing reasons. That we do many things in the world from conjecture is true, but that our redactions are based on conjecture is false. In practical life we are compelled to follow what is most probable; in speculative thought we are compelled to follow truth. A man would perish of hunger and thirst, if he refused to eat or drink, till he had obtained positive proof that food and drink would be good for him. But in philosophic reflection this is not so. On the contrary, we must take care not to admit as true anything, which is only probable. For when one falsity has been let in, infinite others follow.
Again, we cannot infer that because sciences of things divine and human are full of controversies and quarrels, therefore their whole subject-matter is uncertain; for there have been many persons so enamoured of contradiction, as to turn into ridicule geometrical axioms.