I found this little collection of great quotes about drawing and sketching. A couple of my favorites:
“Do not fail, as you go on, to draw something every day, for no matter how little it is, it will be well worthwhile, and it will do you a world of good.” ~ Cennini.
“From the age of six I had a mania for drawing the shapes of things. When I was fifty I had published a universe of designs. but all I have done before the the age of seventy is not worth bothering with. At seventy five I’ll have learned something of the pattern of nature, of animals, of plants, of trees, birds, fish and insects. When I am eighty you will see real progress. At ninety I shall have cut my way deeply into the mystery of life itself. At a hundred I shall be a marvelous artist. At a hundred and ten everything I create; a dot, a line, will jump to life as never before. To all of you who are going to live as long as I do, I promise to keep my word. I am writing this in my old age. I used to call myself Hokosai, but today I sign my self ‘The Old Man Mad About Drawing.’ ” ~ Hokusai, The Drawings of Hokosai.
I love Hokusai.