In the Protreptics this is the 37th Symbol; and Iamblichus has not developed for us the more mystical signification of this symbol. For he only says that “it admonishes us to beware of every thing which is corruptive of our converse with the Gods and divine prophecy.” But Aristotle appears to have assigned the true mystical reason why the Pythagoreans abstained from beans. For he says, (apud Laert.) “that Pythagoras considered beans as a symbol of generation [i. e. of the whole of a visible and corporeal nature,] which subsists according to a right line, and is without inflection; because a bean alone of almost all spermatic plants, is perforated through the whole of it, and is not obstructed by any intervening joints.” Hence he adds, “it resembles the gates of Hades.” For these are perpetually open without any impediment to souls descending into generation. The exhortation, therefore, to abstain from beans, is equivalent to admonishing us to beware of a continued and perpetual descent into the realms of generation. Hence the true meaning of the following celebrated lines in Virgil;
——facilis descensus Averno.
Noctes atque dies patet atri janua Ditis:
Sed revocare gradum, superasque evadere ad auras,
Hoc opus, hic labor est.
i. e.
The gates of Hell are open night and day,
Smooth the descent, and easy is the way;
But to return, and view the cheerful skies,
In this, the mighty task and labor lies.