Toda verdad es fácil de comprender una vez que ha sido descubierta, el problema es descubrirla - Galileo Galilei

You cannot teach a person anything, you can only help him find it within himself.

I entertain no doubts as to the truth of the transfinites, which I have recognized with God's help.

This [experimentation] is the custom—and properly so—in those sciences where mathematical demonstrations are applied to natural phenomena, as is seen in the case of perspective, astronomy, mechanics, music, and others where the principles, once established by well-chosen experiments, become the foundations of the entire superstructure.