On reading each author, I acquired a habit of following all his ideas, without suffering my own or those of any other writer to interfere with them, or entering into any dispute on their utility.

I said to myself, "I will begin by laying up a stock of ideas, true or false, but clearly conceived, till my understanding shall be sufficiently furnished to enable me to compare and make choice of those that are most estimable." I am sensible this method is not without its inconveniences, but it succeeded in furnishing me with a fund of instruction.

Having passed some years in thinking after others, without reflection, and almost without reasoning, I found myself possessed of sufficient materials to set about thinking on my own account, and when journeys of business deprived me of the opportunities of consulting books, I amused myself with recollecting and comparing what I had read, weighing every opinion on the balance of reason, and frequently judging my masters.

Though it was late before I began to exercise my judicial faculties, I have not discovered that they had lost their vigor, and on publishing my own ideas, have never been accused of being a servile disciple or of swearing 'in verba magistri'.
From these studies I passed to the elements of geometry, for I never went further, forcing my weak memory to retain them by going the same ground a hundred and a hundred times over.

I did not admire Euclid, who rather seeks a chain of demonstration than a connection of ideas: I preferred the geometry of Father Lama, who from that time became one of my favorite authors, and whose works I yet read with pleasure.