Mbh 12.332.1b

[1772] Some one else, who is always ready to do acts of injury to all creatures, and who is engaged in deceiving all the world, is seen to wallow in happiness. Some one that sits idly, obtains great prosperity; while another, by exerting earnestly, is seen to miss desirable fruits almost within his reach.[1773] Do thou ascribe it as one of the faults of man! The vital seed, originating in one's nature from sight of one person, goes to another person. When imparted to the womb, it sometimes produces an embryo and sometimes fails. When sexual congress fails, it resembles a mango tree that puts forth a great many flowers without, however, producing a single fruit.[1774] As regards some men who are desirous of having offspring and who, for the fruition of their object, strive heartily (by worshipping diverse deities), they fail to procreate an embryo in the womb. Some person again, who fears the birth of an embryo as one fears a snake of virulent poison, finds a long-lived son born unto him and who seems to be his own self come back to the stages through which he has passed. Many persons with ardent longing for offspring and cheerless on that account, after sacrificing to many deities and undergoing severe austerities, at last beget children, duly borne for ten long months (in the wombs of their spouses), that prove to be veritable wretches of their race. Others, who have been obtained through virtue of such blessed rites and observances, at once obtain wealth and grain and diverse other sources of enjoyment earned and stored by their sires. In an act of congress, when two persons of opposite sexes come into contact with one another, the embryo takes birth in the womb, like a calamity afflicting the mother. Very soon after the suspension of the vital breaths, other physical forms possess that embodied creature whose gross body has been destroyed but whose acts have all been performed with that gross body made of flesh and phlegm.