The best answer I could find is that he thought inspiration came from hard work and discipline. A quote that supports this point would be when he said: "To know what you're going to draw, you have to begin drawing." So, inspirations doesn't just happen by chance.
Answer:
Cel animation is the traditional, hand-drawn animation technique that involves drawing and painting objects on celluloid (cel), a transparent sheet. Nearly all the cartoons in the pre-1990 era were created using cel animation
