Trio in Two Parts (1963) by Stefan Wolpe
for flute, cello, and piano

[From Wolpe letter (1963):]
I am working on the Trio for [Charles] Wuorinen and write an amazing (that is I am amazed) piece of simple events in a less simple, syntactical environment. Long bygone time elements, like etc. I have a horror of exaggerations and long-drawn out grandeur (at this moment). I wonder about the un-weight of leaves, and letters, and facial expressions.

[From another Wolpe letter (1963):]
I am composing a Trio for the Wuorinen group [Group for Contemporary Music], a simple thing (though what can be so simple these days in music). I probably mean music hardened and freed by earlier complexities, by that insatiable pleasure of multiple exposure of progressive facets. I am writing less notes. The time is coordinated on the basis that to each configuration belongs a number of time progressions (variable or extendable), as to the pitch configuration itself belongs characteristic morphological structures (conditions, behavior forms, castlike proportions, reduced dynamics, etc.).