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as laws. For the purely physical laws
are of this nature that they determine accelerations, that is to say what
the position of a particle shall be at a given
instant relatively to its positions at two
instants indefinitely near to the instant
in question; while physiological laws, that is to say,
habits and heredities, simply determine that the
event (usually a complex event) of one time shall
be like the event of a previous time (usually long
previous.) There is also another great difference
between these laws which the majority of those
whose opinions are of weight believe to be
merely apparent, but which I believe to be real.
It is that the purely physical laws are absolutely
compulsive, while the physiological laws are