A multitude of books distracts the mind.

Understanding a question is half an answer.

Better to do a little well, then a great deal badly.

As every divided kingdom falls, so every mind divided between many studies confounds and saps itself.

Focusing is about saying No.

Mathematics, such as appertain to painting, are necessary to the painter, also the absence of companions who are alien to his studies: his brain must be versatile and susceptible to the variety of objects which it encounters, and free from distracting cares.