Plutarch Quaestiones Convivales 6.6.2

[2] Yes, said I, it is a very strange thing, if true. But it is not so; and we cozen ourselves by presently concluding a thing to be hot if it have a faculty of causing heat, when yet we see that the same garment causes heat in winter, and cold in summer. Thus the nurse in the tragedy, The Germans indeed make use of clothes only against the cold, the Ethiopians only against the heat; but they are useful to us upon both accounts. Why therefore should we rather say the clothes are hot, because they cause heat, than cold, because they cause cold? Nay, if we must be tried by sense, it will be found that they are more cold than hot. For at the first putting on of a coat it is cold, and so is our bed when we lie down; but afterwards they grow hot with the heat of our bodies, because they both keep in the heat and keep out the cold. Indeed, feverish persons and others that have a violent heat upon them often change their clothes, because they perceive that fresh ones at the first putting on are much colder; but within a very little time their bodies make them as hot as the others. In like manner, as a garment heated makes us hot, so a covering cooled keeps snow cold. Now that which causes this cold is the continual emanations of a subtile spirit the snow has in it, which spirit, as long as it remains in the snow, keeps it compact and close; but, after once it is gone, the snow melts and dissolves into water, and instantly loses its whiteness, occasioned by a mixture of this spirit with a frothy moisture. Therefore at the same time, by the help of these clothes, the cold is kept in, and the external air is shut out, lest it should thaw the concrete body of the snow. The reason why they make use of cloth that has not yet been at the fuller’s is this, because that in such cloth the hair and coarse flocks keep it off from pressing too hard upon the snow, and bruising it. So chaff lying lightly upon it does not dissolve the body of the snow, besides the chaff lies close and shuts out the warm air, and keeps in the natural cold of the snow. Now that snow melts by the evaporating of this spirit, we are ascertained by sense; for when snow melts it raises a vapor.