It is generally agreed by the most correct writers, that with the earth, as with the birds and quadrupeds, there are certain impulses for reproduction; and the epoch for this is fixed by the Greeks at the time when the earth is warm and moist. Virgil[401] says that wheat and spelt should be sown at the setting of the Vergiliæ, barley between the autumnal equinox and the winter solstice, and vetches,[402] kidney-beans, and lentils at the setting of Boötes:[403] it is of great importance, therefore, to ascertain the exact days of the rising and setting of these constellations, as well as of the others. There are some, again, who recommend the sowing to be done before the setting of the Vergiliæ, but only in a dry soil, and in those provinces where the weather is hot; for the seed, they say,[404] if put in the ground will keep, there being no moisture to spoil it, and within a single day after the next fall of rain, will make its appearance above ground. Others, again, are of opinion that sowing should begin about seven days after the setting of the Vergiliæ, a period which is mostly followed by rain. Some think that cold soils should be sown immediately after the autumnal equinox, and a warm soil later, so that the blade may not put forth too luxuriantly before winter. It is universally agreed, however, that the sowing should not be done about the period of the winter solstice; for this very good reason—the winter seeds, if put in before the winter solstice, will make their appearance above ground on the seventh day, whereas, if they are sown just after it, they will hardly appear by the fortieth. There are some, however, who begin very early, and have a saying to justify their doing so, to the effect that if seed sown too early often disappoints, seed put in too late always does so. On the other hand, again, there are some who maintain that it is better to sow in spring than in a bad autumn; and they say that if they find themselves obliged to sow in spring, they would choose the period that intervenes between the prevalence of the west winds[405] and the vernal equinox. Some persons, however, take no notice of the celestial phenomena, and only regulate their movements by the months. In spring they put in flax, the oat, and the poppy, up to the feast of the Quinquatria,[406] as we find done at the present day by the people of Italy beyond the Padus. There, too, they sow beans and winter-wheat in the month of November, and spelt at the end of September, up to the ides of October:[407] others, however, sow this last after the ides of October, as late as the calends of November.[408]