Yantra
Srimad-Bhagavatam
SB Canto 4
SB 4.23.18, Purport:
Īśvara, the Supreme Personality of Godhead, is situated within the heart of all conditioned souls, and by His supreme will the living entity, or individual soul, gets the facility to lord it over material nature in various types of bodies, which are known as yantra, or the moving vehicle offered by the total material energy, māyā. Although the individual living entity (jīva) and the Lord are both situated within the material energy, the Lord is directing the movements of the jīva soul by offering him different types of bodies through the material energy, and thus the living entity is wandering throughout the universes in various forms of body and becomes implicated in different situations, partaking of the reactions of fruitive activities.