Perspective is the rein and rudder of painting.
One can have no more mastery over the environment, than one has over himself.
The poet ranks far below the painter in the representation of visible things, and far below the musician in that of invisible things.
Do not reveal, if liberty is precious to you; my face is the prison of love.
I have solved what color is, however ; I still have no idea about what line is.
If you find from your own experience that something is a fact and it contradicts what some authority has written down, then you must abandon the authority and base your reasoning on your own findings.