7. Of Twins.

Likewise with regard to the births of two or even more, it is fitting to observe the same two places, that is, the two luminaries and the horoscope. For such an event is apt to attend the intermixture when either two or the three places cover bicorporeal signs, and particularly when the same is true of the planets that rule them, or when some are in bicorporeal signs, and some are disposed in pairs or in larger groups. But when both the dominant places are in bicorporeal signs and most of the planets are similarly configurated, then it befalls that even more than top are conceived, for the number is conjectured from the star that causes the peculiar property of the number, and the sex from the aspects which the planets have with respect to the sun and the moon and the horoscope for the production of males or of females, in accordance with the ways stated above. But whenever such an arrangement of the planets does not include the horoscopic angle with the luminaries, but rather that of the mid-heaven, mothers with such genitures generally conceive twins or even more; and in particular, they give multiple birth, to three males, by the geniture of the Kings, when Saturn, Jupiter, and Mars are in bicorporeal signs and bear same aspect to the aforesaid places; and to three females, by the geniture of the Graces, when Venus and the moon, with Mercury made feminine, are so arranged; to two males and One female, by the geniture of the Dioscuri, when Saturn, Jupiter, and Venus are so ordered, and to two females and a male, by the geniture of Demeter and Korê, when Venus, the moon, and Mars are thus ordered. In these cases it generally happens that the children are not completely developed and are born with certain bodily marks, and again the governing places may bear certain unusual and surprising marks by reason of the divine manifestation, as it were, of such portents.

Ptolemy's Tetrabiblos

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