Krsna & the cows & bulls

[Bhakti Vikasa Swami]

Lord Krsna, as the teacher of human society, personally showed by His acts that
the mercantile community, or the vaisyas, should herd cows and bulls and thus
give protection to the valuable animals. According to smrti regulation, the cow
is the mother and the bull the father of the human being. The cow is the mother
because just as one sucks the breast of one's mother, human society takes cow's
milk. Similarly, the bull is the father of human society because the father
earns for the children just as the bull tills the ground to produce food
grains. Human society will kill its spirit of life by killing the father and
the mother. It is mentioned herein that the beautiful cows and bulls were of
various checkered colors -- red, black, green, yellow, ash, etc. And because of
their colors and healthy smiling features, the atmosphere was enlivening.
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From Srila Prabhupada's purport to SB 3.2.29