René Descartes (A translation)

Quaecumque sub perceptionem nostram cadunt, vel tanquam res, rerumue affectiones quasdam, consideramus; vel tanquam aeternas ueritates, nullam existentiam extra cogitationem nostram habentes.

Cum autem agnoscimus fieri non posse, ut ex nihilo aliquid fiat, tunc propositio haec: Ex nihilo nihil fit, non tanquam res aliqua existens, neque etiam ut rei modus consideratur, sed ut veritas quaedam aeterna, quae in mente nostra sedem habet, vocaturque communis notio, siue axioma. Cuius generis sunt: Impossibile est idem simul esse et non esse: Quod factum est, infectum esse nequit: Is qui cogitat, non potest non existere dum cogitat: et alia innumera, quae quidem omnia recenseri facile non possunt...

Whatever things fall under our perception we consider as (1) things or the affections of things, or (2) as eternal truths, that have no existence outside our thoughts.

But when we recognize that something is not able to be made out of nothing, then the proposition: “Ex nihilo nihil fit” is not a thing that exists, nor even considered as a mode of something, but as a kind of eternal truth, having its seat in our mind, and is known as a common axiom or notion. Of this class are: “It is impossible simultaneously to be and not to be; What is done, cannot be undone; The man who thinks is not able to not exist when he thinks [He who thinks must exist when he thinks];” and innumerable others, all of which cannot be easily counted...