sensations--as for example those due to fetal movements--which are so
distinctive that they cannot escape notice. These obvious evidences
of approaching motherhood naturally lead thoughtful women to wonder
about the hidden mechanism of development, a mechanism which, of
itself, causes no sensation whatever. It is for this reason, perhaps,
that a prospective mother's imagination is so apt to be unusually
active, often picturing absurd conditions as responsible for one
symptom or another. Those who give free play to the imagination in
regard to the formation and progress of the embryo are pretty certain
to arrive at erroneous if not grotesque conclusions; for example,
they may attribute a protracted pregnancy to the child's having grown
fast to the mother, a situation that cannot arise.

Of course it is not essential that a prospective mother should
understand what is happening within the womb. And upon those who
prefer to be ignorant of the mechanism of development I would not
urge another point of view, for not ignorance but the unchallenged
acceptance of "half-truths" and of totally incorrect explanations is
the chief source of harm. On the other hand, my own experience has
taught me that women who wish to know about development should be
told the truth. In accord with this is the fact that I never have
more satisfactory patients than those who have previously been
trained nurses and who, in preparing for that profession, received
instruction concerning the reproductive function of human beings.

A description of development, in order to be perfectly clear, must
begin with a word about the fundamental structure of the adult body.
Everyone knows that the various parts of the body perform different
functions; but not everyone, perhaps, realizes that, in spite of
their different functions, all the organs of the body are composed of