Plutarch's Symposiacs by Plutarch

1. At a supper in Elis, Agemachus set before us very large mushrooms. And when all admired at them, one with a smile said, These are worthy the late thunder, as it were deriding those who imagine mushrooms are produced by thunder. Some said that thunder did split the earth, using the air as a wedge for that purpose, and that by those chinks those that sought after mushrooms were directed where to find them; and thence it grew a common opinion, that thunder engenders mushrooms, and not only makes them a passage to appear; as if one should imagine that a shower of rain breeds snails, and not rather makes them creep forth and be seen abroad. Agemachus stood up stiffly for the received opinion, and told us, we should not disbelieve it only because it was strange, for there are a thousand other effects of thunder and lightning and a thousand omens deduced from them, whose causes it is very hard, if not impossible, to discover; for this laughed-at, this proverbial mushroom doth not escape the thunder because it is so little, but because it hath some antipathetical qualities that preserve it from blasting; as likewise a fig-tree, the skin of a sea-calf (as they say), and that of the hyena, with which sailors cover the ends of their sails. And husbandmen call thunder-showers fertilizing, and think them to be so. Indeed, it is absurd to wonder at these things, when we see the most incredible things imaginable in thunder, as flame rising out of moist vapors, and from soft clouds such astonishing noises. Thus, he continued, I prattle, exhorting you to enquire after the cause; and I shall accept this as your club for these mushrooms.

2. Then I began: Agemachus himself helps us exceedingly toward this discovery; for nothing at the present seems more probable than that, together with the thunder, oftentimes generative waters fall, which receive that quality from the heat mixed with them. For the piercing pure parts of the fire break away in lightning; but the grosser flatulent part, being wrapped up in the cloud, changes its nature, taking away the coldness and rendering the moisture mild and gentle, and altering and being altered with it, warms it so that it is made fit to enter the pores of plants, and is easily assimilated to them. Besides, such rain gives those things which it waters a peculiar temperature and difference of juice. Thus dew makes the grass sweeter to the sheep, and the clouds from which a rainbow is reflected make those trees on which they fall fragrant. And our priests, distinguishing it by this, call the wood of those trees rainbow-struck, imagining that Iris, or the rainbow, hath rested on them. Now it is probable that when these thunder and lightning showers with a great deal of warmth and spirit descend forcibly into the caverns of the earth, the ground is moved thereby, and knobs and tumors are formed like those produced by heat and noxious humors in our bodies, which we call wens or kernels. For a mushroom is not like a plant, neither is it produced without rain; it hath no root nor sprouts, it depends on nothing, but is a being by itself, having the consistence only of the earth, which hath been a little changed and altered. If this discourse seems frivolous, I assure you that such are most of the effects of thunder and lightning which we see; and upon that account men think them to be immediately directed by Heaven, and not depending on natural causes.