After this, I investigated what is essential for a proposition to be true and certain. Since I had found one proposition that I knew was true, I believed I should be able to find the basis for this certainty as well.
After this I inquired in general into what is essential to the truth and certainty of a proposition; for since I had discovered one which I knew to be true, I thought that I must likewise be able to discover the ground of this certitude.
