In plain words
there is no rule that they must live in the hills. What must happen, where, why, and when -- its ordainer, the Lord of all, alone knows. Not everyone can determine that. Birth and the like are related to circumstances of place, time and karma, but they do not fall under our own categories of favourable and unfavourable. To an intellect that lives taking only the directly perceptible as its basis, a doubt may well arise -- 'what is this matter of varṇa?' -- and that is natural. This very thing is called ego. The true nature of a thing is one matter, and ego is another. Setting out to act, and beginning to speak, just as one's own mind pleases, without knowing the true nature of a thing -- this may well be called a mark of ignorance.