In plain words
Not only that — it must also be of gentle temperament. We choose only a cow that possesses such good qualities; but no one, knowing better, would ever pick out, merely because it belongs to the cow-species, a barren cow that gives no milk and lacks such gentle qualities. Here, the quality of cow-ness is equally present in every single cow. Our choice does not rest on outward sameness of shape but on breed, colour, temperament and the like. Is that not so? In just the same way, though the human race is one in form, it too rests on differences of temperament and the like — that is the very matter we must understand.
On another point: if we go a little deeper and examine the matter, the notions of 'high' and 'low' turn out to be unavoidably natural. Although there is not the slightest actual difference between excreta as such, people consider the urine and dung of a cow alone to be pure, while regarding the dung and urine of other creatures as impure. It is just the same with fire. Fire is simply fire; the properties within it are one and the same. Yet the distinction between the exalted and the base cannot but persist. In our own homes we light a lamp, we kindle the hearth, and in yajnas and sacred rites we kindle fire for the oblation — and this fire we consider pure, we regard as the very form of the Divine, we worship it, we bow to it. That very same fire, when it is burning a corpse in the cremation ground, we seek no help from at all. We do not bow to it, we do not bake our bread in it, we do not light our lamp from it. Why? Because we consider it impure — that is simply our own notion. It is exactly the same with man. Though all are alike in form, depending on the body and other outer conditions, and on differences of character and conduct, we are compelled to call this man superior and that man inferior. The electric current is one and the same, yet depending on the differing construction of the bulbs, we constantly see differences — of brighter and dimmer — in the light they give. The above matters,