There is nothing so absurd that it has not been said by some philosopher.

Nothing is too absurd for some philosopher to have said it.

There is nothing so absurd that some philosopher has not already said it.

There is nothing so strange and so unbelievable that it has not been said by one philosopher or another.

Descartes’ dictum: ‘There is nothing so absurd or incredible that it has not been asserted by one philosopher or another.

I had become aware, as early as my college days, that no opinion, however absurd and incredible can be imagined, that has not been held by one of the philosophers.

Nothing can be imagined which is too strange or incredible to have been said by some philosopher.

Credere quia absurdum est

Nihil est sine ratione.
[There is nothing without a reason.]

Nil mortalibus ardui est

"Scio me nihil scire" - I know that I know nothing

nil sine magno vita labore dedit mortalibus

O vitae Philosophia dux! O virtutum indagatrix expultrixque vitiorum! Unus dies, bene et ex praeceptis tuis actus, peccanti immortalitati est anteponendus.

translation (non-literal):
O philosophy, life’s guide! O searcher of virtues and expeller of vices! Just a single day lived well and according to your lessons is to be preferred to an eternity of errors. — Cicero, As quoted in Ben Franklin’s Autobiography

A philosopher worthy of the name has never said more than a single thing: and even then it is something he has tried to say, rather than actually said. And he has said only one thing because he has seen only one point: and at that it was not so much a vision as a contact: this contact has furnished an impulse, this impulse a movement, and if this movement, which is as it were a kind of swirling of dust taking a particular form, becomes visible to our eyes only through what it has collected along its way, it is no less true that other bits of dust might as well have been raised and that it would still have been the same whirlwind. Thus a thought which brings something new into the world is of course obliged to manifest itself through the ready-made ideas it comes across and draws into its movement; it seems thus, as it were, relative to the epoch in which the philosopher lived; but that is frequently merely an appearance. The philosopher might have come several centuries earlier; he would have had to deal with another philosophy and another science; he would have given himself other problems; he would have expressed himself by other formulas; not one chapter perhaps of the books he wrote would have been what it is; and nevertheless he would have said the same thing.