SB 10.20.41
kedarebhyas tv apo ’grhnan
karsaka drdha-setubhih
yatha pranaih sravaj jñanam
tan-nirodhena yoginah
Translation:
In the same way that the practitioners of yoga bring their senses under strict control to check their consciousness from flowing out through the agitated senses, the farmers erected strong mud banks to keep the water within their rice fields from draining out.
Purport:
Srila Prabhupada comments: “In autumn, farmers save the water within the fields by building strong walls so that the water contained within the field cannot run out. There is hardly any hope for new rainfall; therefore they want to save whatever is in the field. Similarly, a person who is actually advanced in self-realization protects his energy by controlling the senses. It is advised that after the age of fifty one should retire from family life and conserve the energy of the body for utilization in the advancement of Krsna consciousness. Unless one is able to control the senses and engage them in the transcendental loving service of Mukunda, there is no possibility of salvation.”