Phillip Sidney's ________, the most important piece of literary criticism in the sixteenth century, defines the major literary modes or kinds available to writers: pastoral, heroic, lyric, satiric, elegiac, tragic, and comic. The poetic conventions of these modes helped to shape poetry's subject matter, attitude, tone, and values; in some cases (e.g., the sonnet), they also governed formal structure, meter, style, length, and occasion.