Plutarch, De Iside et Osiride
Frank Cole Babbitt, Ed.

In this way we shall undertake to deal with the numerous and tiresome people, whether they be such as take pleasure in associating theological problems with the seasonal changes in the surrounding atmosphere, or with the growth of the crops and seedtimes and ploughing ; and also those who say that Osiris is being buried at the time when the grain is sown and covered in the earth and that he comes to life and reappears when plants begin to sprout. For this reason also it is said that Isis, when she perceived that she was pregnant, put upon herself an amulet¹ on the sixth day of the month Phaophi ; and about the time of the winter solstice she gave birth to Harpocrates, imperfect and premature,² amid the early flowers and shoots. For this reason they bring to him as an offering the first-fruits of growing lentils, and the days of his birth they celebrate after the spring equinox. When the people hear these things, they are satisfied with them and believe them, deducing the plausible explanation directly from what is obvious and familiar.