I have concluded the evident existence of God, and that my existence depends entirely on God in all the moments of my life, that I do not think that the human spirit may know anything with greater evidence and certitude.

Whatever I have up till now accepted as most true and assured I have gotten either from the senses or through the senses. But from time to time I have found that the senses deceive, and it is prudent never to trust completely those who have deceived us even once.

We never understand a thing so well,and make it our own, as when we have discovered it for ourselves.

It is contrary to reasoning to say that there is a vacuum or space in which there is absolutely nothing.

With me, everything turns into mathematics.

The rainbow is such a remarkable phenomenon of nature, and its cause has been so meticulously sought after by inquiring minds throughout the ages, that I could not choose a more appropriate subject for demonstrating how, with the method I am using, we can arrive at knowledge not possessed at all by those whose writings are available to us.

At last I will devote myself sincerely and without reservation to the general demolition of my opinions.