John asked:

A certain philosopher used a device to determine the sex of an unborn child. Who was this person
and what device did they use? Any help you can give me will be greatly appreciated.

and Jeff asked:

A philosopher had a theory that determined the best time to conceive a child of a certain sex. Who
was the philosopher and what was the device used to determine the proper time to conceive?

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Girls are more likely to be conceived than boys when the moon is on the wane according to Aristotle,
or at least the Aristotle of 'Aristotle's Masterpiece'.

'Aristotle's Masterpiece' is a sort of handbook to midwifery composed in the late seventeenth century;
there is a good discussion of it in Ch. 2 of Roy Porter & Lesley Hall's The Facts of Life(Yale, 1995). It
was a popular work for many years, but it has confused and obscure origins: it is unclear when it was
written, by whom it was written and even in what language it was written. But we do know that it had
little or nothing to do with Aristotle. He might have actually said something along these lines, perhaps
in his De Generatione Animalium,but I wouldn't attribute the view to him without further checking.

Andrew Aberdein
Dept of Logic and Metaphysics
University of St Andrews
Fife, Scotland.

St. Augustine, in the City of God,has a discussion of the Roman practice of timing conception to
determine the attributes of offspring. He considers the practice, which was linked to astrological
beliefs, to be without any factual foundation. However, since the differential motility of male and
female sperm means that the timing of intercourse relative to ovulation does have at least a statistical
influence on the sex of offspring, such a belief may not be entirely without foundation.

Martha Sherwood
Ecology and Evolution Program
University of Oregon