There are operations of extreme length in which I have sometimes seen good geometricians lose themselves.

Reflection, assisted by practice, gives clear ideas, and enables you to devise shorter methods, these inventions flatter our self-complacency, while their exactitude satisfies our understanding, and renders a study pleasant, which is, of itself, heavy and unentertaining.
At length I became so expert as not to be puzzled by any question that was solvable by arithmetical calculation; and even now, while everything I formerly knew fades daily on my memory, this acquirement, in a great measure remains, through an interval of thirty years.

A few days ago, in a journey I made to Davenport, being with my host at an arithmetical lesson given his children, I did (with pleasure, and without errors) a most complicated work.

While setting down my figures, methought I was still at Chambery, still in my days of happiness--how far had I to look back for them! The colored plans of our geometricians had given me a taste for drawing: accordingly I bought colors, and began by attempting flowers and landscapes.

It was unfortunate that I had not talents for this art, for my inclination was much disposed to it, and while surrounded with crayons, pencils, and colors, I could have passed whole months without wishing to leave them.