The virtue of the soul does not consist in flying high, but in walking orderly; its grandeur does not exercise itself in grandeur, but in mediocrity.

Montaigne

Man is a small kosmos.

Democritus, (per Philip Wheelwright, The PreSocratics)

In everything there is a portion of everything else.

Anaxagoras, (per Philip Wheelwright, The PreSocratics)

The justice which in itself is natural and universal is otherwise and more nobly ordered than that other justice which is special, national, and constrained to the ends of government.

Montaigne

Content yourself ... to swim in troubled waters without fishing in them.

Montaigne

I do not disapprove the use we make of things the earth produces, nor doubt, in the least, of the power and fertility of Nature, and of its application to our necessities: I very well see that pikes and swallows live by her laws; but I mistrust the inventions of our mind, our knowledge and art, to countenance which, we have abandoned Nature and her rules, and wherein we keep no bounds nor moderation. 

Montaigne

To be is possible and not-to-be is impossible.... Thought and being are the same.

Parmenides, (per Philip Wheelwright, The PreSocratics)

Everything flows and nothing abides; everything gives way and nothing stays fixed.... It is in changing that things find repose.

Men who love wisdom should acquaint themselves with a great many particulars.

Heraclitus (per Philip Wheelwright, The PreSocratics)

The internet reminds us on a daily basis that it is not at all rewarding to become aware of problems that you have no reasonable hope of solving.

Jia Tolentino, as quoted in the New York Review by Jonathan Lethem

Exponential growth inside a finite system leads to collapse.

Richard Powers, The Overstory