Plutarch, De Iside et Osiride
Goodwin, Ed.

And therefore the desire of truth, especially in what relates to the Gods, is a sort of grasping after divinity, it using learning and enquiry for a kind of resumption of things sacred, a work doubtless of more religion than any ritual purgation or charge of temples whatever, and especially most acceptable to the Goddess you serve, since she is more eminently wise and speculative, and since knowledge and science (as her very name¹ seems to import) appertain more peculiarly to her than any other thing. For the name of Isis is Greek, and so is that of her adversary Typhon, who, being puffed up² through ignorance and mistake, pulls in pieces and destroys that holy doctrine, which she on the contrary collects, compiles, and delivers down to such as are regularly advanced unto the deified state; which, by constancy of sober diet, and abstaining from sundry meats and the use of women, both restrains the intemperate and voluptuous part, and habituates them to austere and hard services in the temples, the end of which is the knowledge of the original, supreme, and mental being, which the Goddess would have them enquire for, as near to herself and as dwelling with her. Besides, the very name of her temple most apparently promises the knowledge and acquaintance of true being (τὸ ὄν), for they call it Iseion (῎Ισειον), as who should say, We shall know true being, if with reason and sanctimony we approach the sacred temples of this Goddess.