The principle of moderation in Morals is represented by the ancients in the path which Icarus was directed to take through the air; the same principle in relation to the intellect, by the passage between Scylla and Charybdis, so famous for its difficulty and danger.
Icarus was instructed by his father to beware, when he came to fly over the sea, of taking either too high or too low a course. For his wings being fixed on with wax, the fear was that if he rose too high the wax would be melted by the suns heat; if he kept down too near the vapour of the sea, it would lose its tenacity by the moisture. Icarus, in the adventurous spirit of youth, made for the heights, and so fell headlong down.
It is an easy and a familiar parable. The path of virtue goes directly midway between excess on the one hand and defect on the other. Icarus, being in the pride of youthful alacrity, naturally fell a victim to excess. For it is on the side of excess that the young commonly sin, as the old on the side of defect. And yet if he was to perish one way, it must be admitted that of two paths, both bad and mischievous, he chose the better. For sins of defect are justly accounted worse than sins of excess; because in excess there is something of magnanimity,something, like the flight of a bird, that holds kindred with heaven; whereas defect creeps on the ground like a reptile. Excellently was it said by Heraclitus, Dry light is the best soul. For when the moisture and humours of earth get into the soul, it becomes altogether low and degenerate. And yet here too a measure must be kept: the dryness, so justly praised, must be such as to make the light more subtle, but not such as to make it catch fire. But this is what everybody knows.
Now for the passage between Scylla and Charybdis (understood of the conduct of the understanding) certainly it needs both skill and good fortune to navigate it. For if the ship run on Scylla, it is dashed on the rocks, if on Charybdis, it is sucked in by the whirlpool: by which parable (I can but briefly touch it, though it suggests reflexions without end) we are meant to understand that in every knowledge and science, and in the rules and axioms appertaining to them, a mean must be kept between too many distinctions and too much generality,between the rocks of the one and the whirlpools of the other. For these two are notorious for the shipwreck of wits and arts.