mādhuryas tīrtha-bhūr nṛṇām
muniḥ punāty apāṁ mitram
The words apāṁ mitram, “just like water,” can also be read as aghān mitram, which means that a saintly person purifies all living entities by accepting them as mitram, or his personal friends, and saves them from their sinful reactions (aghāt). The conditioned living entity falsely identifies with his gross material body and subtle mind and thus falls from the platform of spiritual knowledge. A conditioned living being is always lusty for material sense gratification, and if he does not acquire it, he becomes angry. Sometimes he is so obsessed with fear of losing his material gratification that he enters a stage approaching madness.
A saintly person, however, is like pure water, free from all contamination and capable of purifying all things. Just as pure water is transparent, a saintly person transparently manifests the Personality of Godhead within his heart. Such love of Godhead is the reservoir of all happiness. Water makes a most pleasing vibration as it flows and cascades, and similarly the sound vibration of the Lord’s pure devotee, who is saturated with the glories of the Lord, is most charming and beautiful. Thus, by studying the nature of water one can understand the symptoms of a pure devotee of the Lord.