The materially absorbed mind of the conditioned soul does not allow him to transcend the limit of the bodily conception of self, and thus the yoga system for meditation (controlling the sitting posture and breathing process and fixing the mind upon the Supreme) is prescribed in order to mold the character of the gross materialist.
Unless such materialists are able to cleanse the materially absorbed mind, it is impossible for them to concentrate upon thoughts of transcendence. And to do so one may fix one’s mind on the gross material or external feature of the Lord. The different parts of the gigantic form of the Lord are described in the following verses. The materialistic men are very anxious to have some mystic powers as a result of such a controlling process, but the real purpose of yogic regulations is to eradicate the accumulated dirty things like lust, anger, avarice and all such material contaminations. If the mystic yogī is diverted by the accompanying feats of mystic control, then his mission of yogic success is a failure, because the ultimate aim is God realization. He is therefore recommended to fix his gross materialistic mind by a different conception and thus realize the potency of the Lord. As soon as the potencies are understood to be instrumental manifestations of the transcendence, one automatically advances to the next step, and gradually the stage of full realization becomes possible for him.
Ref >> Srila Prabhupada Vani.