there is often not so much perfection in works composed of many pieces and made by the hands of various master craftsmen as there is in those works o… - René Descartes

I doubt, therefore I think, therefore I am.

Thus, all unknown quantities can be expressed in terms of a single quantity, whenever the problem can be constructed by means of circles and straight lines, or by conic sections, or even by some other curve of degree not greater than the third or fourth.
But I shall not stop to explain this in more detail, because I should deprive you of the pleasure of mastering it yourself, as well as of the advantage of training your mind by working over it, which is in my opinion the principal benefit to be derived from this science. Because, I find nothing here so difficult that it cannot be worked out by anyone at all familiar with ordinary geometry and with algebra, who will consider carefully all that is set forth in this treatise.

Κυρίως μου άρεσαν τα μαθηματικά, για τη βεβαιότητα και το προφανές της τεκμηρίωσης τους όμως εξακολουθούσα να μην αντιλαμβάνομαι καθόλουτη πραγματική χρησιμότητα τος και, θεωρώντας ότι δεν χρησίμευαν παρά μόνο στις μηχανικές τέχνες.