He who is fixed to a star does not change his mind. - Leonardo da Vinci

Though I may not, like them, be able to quote other authors, I shall rely on that which is much greater and more worthy — on experience, the mistress of their Masters. They go about puffed up and pompous, dressed and decorated with [the fruits], not of their own labours, but of those of others. And they will not allow me my own. They will scorn me as an inventor; but how much more might they — who are not inventors but vaunters and declaimers of the works of others — be blamed.

He who possesses most must be most afraid of loss.

There is no certainty in sciences where one of the mathematical sciences cannot be applied, or which are not in relation with these mathematics.