Yōga Sūtra 1.04

वृत्तिसारूप्यमितरत्र।

vr̥ttisārūpyamitaratra।

[वृत्ति सारूप्यम् इतरत्र।
vr̥tti = involved activity; sārūpyam = assumes the form of; itaratra = at other times;]

At other times, it assumes the form of involved activity.

When a person is not conscious and aware of what mind is doing, he/she has become mind and is engaged in activity (vritti). E.g. Person enjoying the music.