Mbh 12.237.3b

It is wisdom or knowledge that is the highest refuge of all things.[926] All the diverse kinds of created things have four kinds of birth. They are viviparous, oviparous, vegetables, and those born of filth. Creatures, again, that are mobile should be known to be superior to those that are immobile. It is consistent with reason that intelligent energy, inasmuch as it differentiates (all non-intelligent matter), should be regarded as superior to (non-intelligent) matter.[927] Mobile creatures, that are innumerable, are of two kinds, viz., those that have many legs and those that have two. The latter, however, are superior to the former. Bipeds, again are of two species, viz., those that live on land and those that are otherwise. Of these, the former are superior to the latter. The superior ones eat diverse kinds of cooked food.[928] Bipeds moving on land are of two kinds viz., middling or intermediate, and those that are foremost. Of these, the middling or intermediate are regarded as superior (to the former) in consequence of their observance of the duties of caste.[929] The middling or intermediate ones are said to be of two kinds, viz., those that are conversant with duties, and those that are otherwise. Of those, the former are superior in consequence of their discrimination in respect of what should be done and what should not. Those conversant with duties are said to be of two kinds, viz., those that are acquainted with the Vedas and those that are otherwise. Of these the former are superior, for the Vedas are said to dwell in them.[930] Those that are acquainted with the Vedas are said to be of two kinds, viz., those that lecture on the Vedas and those that are otherwise. Of these, the former, who are fully conversant with the Vedas, with the duties and the rites laid down in them, and the fruits of those duties and rites, are superior in consequence of their publishing all those duties and rites.