PURPORT

As stated in the Brahma-samhita (5.33):

advaitam acyutam anadim ananta-rupam
adyam purana-purusam nava-yauvanam ca
vedesu durlabham adurlabham atma-bhaktau
govindam adi-purusam tam aham bhajami

"I worship the Supreme Personality of Godhead, Govinda, who is the original person-nondual, infallible, and without beginning. Although He expands into unlimited forms, He is still the original, and although He is the oldest person, He always appears as a fresh youth. Such eternal, blissful and all-knowing forms of the Lord cannot be understood by the academic wisdom of the Vedas, but they are always manifest to pure, unalloyed devotees."

While decorating the body with tilaka, we give protection to the body by chanting twelve names of Visnu. Although Govinda, or Lord Visnu, is one, He has different names and forms with which to act differently. But if one cannot remember all the names at one time, one may simply chant, "Lord Visnu, Lord Visnu, Lord Visnu," and always think of Lord Visnu. Visnor aradhanam param : this is the highest form of worship. If one remembers Visnu always, even though one is disturbed by many bad elements, one can be protected without a doubt. The Ayurveda-sastra recommends, ausadhi cintayet visnum: even while taking medicine, one should remember Visnu, because the medicine is not all and all and Lord Visnu is the real protector. The material world is full of danger (padam padam yad vipadam). Therefore one must become a Vaisnava and think of Visnu constantly. This is made easier by the chanting of the Hare Krsna maha-mantra. Therefore Sri Caitanya Mahaprabhu has recommended, kirtaniyah sada harih param vijayate sri-krsna-saṅkirtanam, and kirtanad eva krsnasya mukta-saṅgah param vrajet.