修習止觀坐禪法要 1.77

1.77

夫入定本是從麁入細，是以身既為麁，息居其中，心最為細靜。調麁就細，令心安靜，此則入定初方便也。是名初入定時調三事也。

Entering concentration originally proceeds from the coarse to the subtle: therefore, the body being coarse, the breath being in between, and the mind being the most subtle and tranquil, harmonizing the coarse to approach the subtle and causing the mind to become tranquil is the initial expedient means for entering concentration. This is called harmonizing the three things upon first entering concentration.