Plutarch, De Iside et Osiride 79 (part 2)

ὤνησε γὰρ οὐκ ὀλίγους. Ἀριστοτέλης δέ φησι καὶ μύρων καὶ ἀνθέων καὶ λειμώνων εὐώδεις ἀποπνοίας οὐκ ἔλαττον ἔχειν τοῦ πρὸς ἡδονὴν τὸ πρὸς ὑγίειαν, ψυχρὸν ὄντα φύσει καὶ παγετώδη τὸν ἐγκέφαλον ἠρέμα τῇ θερμότητι καὶ λειότητι διαχεούσας. εἰ δὲ καὶ τὴν σμύρναν παρʼ Αἰγυπτίοις βὰλ καλοῦσιν, ἐξερμηνευθὲν δὲ τοῦτο μάλιστα φράζει τῆς ληρήσεως ἐκσκορπισμόν, ἔστιν ἣν καὶ τοῦτο μαρτυρίαν τῷ λόγῳ τῆς αἰτίας δίδωσιν.

If, as I have promised, I must now speak of the offerings of incense which are made each day, one should first consider that this people always lays the very greatest stress upon those practices which are conducive to health. Especially in their sacred services and holy living and strict regimen the element of health is no less important than that of piety. For they did not deem it proper to serve that which is pure and in all ways unblemished and unpolluted with either bodies or souls that were unhealthy and diseased. Since, then, the air, of which we make the greatest use and in which we exist, has not always the same consistency and composition, but in the night-time becomes dense and oppresses the body and brings the soul into depression and solicitude, as if it had become befogged and heavy, therefore, immediately upon arising, they burn resin on their altars, revivifying and purifying the air by its dissemination, and fanning into fresh life the languished spirit innate in the body, inasmuch as the odour of resin contains something forceful and stimulating. Again at midday, when they perceive that the sun is forcibly attracting a copious and heavy exhalation from the earth and is combining this with the air, they burn myrrh on the altars; for the heat dissolves and scatters the murky and turgid concretions in the surrounding atmosphere. In fact, physicians seem to bring relief to pestilential affections by making a large blazing fire, for this rarefies the air. But the rarefication is more effective if they burn fragrant woods, such as that of the cypress, the …