Srila Prabhupada's lotus feet

The lotus feet of our spiritual master are the only way by which we can attain pure devotional service. I bow to his lotus feet with great awe and reverence. By his grace one can cross the ocean of material suffering and obtain the mercy of Krishna.”
(Sri Guru-vandana Verse 1, Srila Narottama dasa Thakura)

“The dust of the feet of a devotee, the water that has washed the feet of a devotee, and the remnants of food left by a devotee are three very powerful substances. By rendering service to these three, one attains the supreme goal of ecstatic love for Krishna. In all the revealed scriptures this is loudly declared again and again. Therefore, my dear devotees, please hear from me, for I insist again and again: please keep faith in these three and render service to them without hesitation. From these three one achieves the highest goal of life – ecstatic love of Krishna. This is the greatest mercy of Lord Krishna.”
(Chaitanya-charitamrita Antya 16.60-63)

Srila Prabhupada's lotus feet

“In the neophyte stage, in the intermediate stage, or in the fully advanced perfected stage, one can make the function of the head perfect by bowing down before the Lord or His representative. Similarly, he can perfect the function of the eyes by seeing the Lord and His representative. In this way, everyone can elevate the functions of the different parts of his body to the highest perfectional stage simply by engaging them in the service of the Lord or His representative. If one is able to do nothing more, he can simply bow down before the Lord and His representative and drink the charanamrita, the water which has washed the lotus feet of the Lord or His devotee.”
(Krishna Book, Chapter 80)

Source: http://krishnaconsciousnessmovement.com/?p=15011