The process of meditation should begin from the lotus feet of the Lord and progress to His smiling face. The meditation should be concentrated upon the lotus feet, then the calves, then the thighs, and in this way higher and higher. The more the mind becomes fixed upon the different parts of the limbs, one after another, the more the intelligence becomes purified.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
एकैकशोऽङ्गानि धियानुभावयेत्- पादादि यावद्धसितं गदाभृतः । जितं जितं स्थानमपोह्य धारयेत् परं परं शुद्ध्यति धीर्यथा यथा
ekaikaśo'ṅgāni dhiyānubhāvayet- pādādi yāvaddhasitaṃ gadābhṛtaḥ | jitaṃ jitaṃ sthānamapohya dhārayet paraṃ paraṃ śuddhyati dhīryathā yathā
SB 2.2.13