Serious color studies of nudes and heads. Only as practice and first training. Very strict determination of color values through water color. On top … - Paul Klee

The work grows "stone upon stone" (additive) or
The block is hewn "chip from chip" (subtractive)
Both processes, building and reducing, are time bound.

What had already been done for music by the end of the eighteenth century has at last been begun for the pictorial arts. Mathematics and physics furnished the means in the form of rules to be followed and to be broken. In the beginning it is wholesome to be concerned with the functions and to disregard the finished form. Studies in algebra, in geometry, in mechanics characterize teaching directed towards the essential and the functional, in contrast to apparent. One learns to look behind the façade, to grasp the root of things. One learns to recognize the undercurrents, the antecedents of the visible. One learns to dig down, to uncover, to find the cause, to analyze.

And now an altogether revolutionary discovery: to adapt oneself to the contents of the paintbox is more important than [to] nature and its study. I must some day be able to improvise freely on the chromatic keyboard of the rows of watercolor cup.