The constant human equivalent of the element of form in art is the sense of beauty. What is unchanging is sensibility. What changes is the understanding that human beings build for themselves by abstracting their perceptions and mental life, and we owe the variable element in art, namely expression, to this.

A work of art is, in a way, the liberation of personality. Normally, our emotions are suppressed and reined in. When we focus on a work of art, there is suddenly an outpouring. This is not just an outpouring – sympathy is also an outpouring of emotions – but also an elevation, a tension, and a sublimation. This is the difference between art and sentimentality: sentimentality is an outpouring, but also a loosening and relaxation of emotions. Art, on the other hand, is an outpouring, but also a restraint. Art is a thrifty emotion, an excitement that creates good form.
(From the Promotional Bulletin)