’III.  The difficulty will be greater still, if it be considered that the human machine contains an almost infinite number of organs, and that it is continually exposed to the shock of the bodies that surround it,[1] and which by an innumerable variety of shakings produce in it a thousand sorts of modifications.  How is it possible to conceive that this pre-established harmony should never be disordered, but go on still during the longest life of a man, notwithstanding the infinite varieties of the reciprocal action of so many organs upon one another, which are surrounded on all sides with infinite corpuscles, sometimes hot and sometimes cold, sometimes dry and sometimes moist, and always acting, and pricking the nerves a thousand different ways?  Suppose that the multiplicity of organs and of external agents be a necessary instrument of the almost infinite variety of changes in a human body:  will that variety have the exactness here required?  Will it never disturb the correspondence of those changes with the changes of the soul?  This seems to be altogether impossible.

[1] ’According to M. Leibniz what is active in every substance ought to be reduced to a true unity.  Since therefore the body of every man is composed of several substances, each of them ought to have a principle of action really distinct from the principle of each of the others.  He will have the action of every principle to be spontaneous.  Now this must vary the effects ad infinitum, and confound them.  For the impression of the neighbouring bodies must needs put some constraint upon the natural spontaneity of every one of them.’

’IV.  It is in vain to have recourse to the power of God, in order to maintain that brutes are mere machines; it is in vain to say that God was able to make machines so artfully contrived that the voice of a man, the reflected light of an object, etc., will strike them exactly where it is necessary, that they may move in a given manner.  This supposition is rejected by everybody except some Cartesians; and no Cartesian would admit it if it were to be extended to man; that is, if anyone were to assert that God was able to form such bodies as would mechanically do whatever we see other men do.  By denying this we do not pretend to limit the power and knowledge of God:  we only mean that the nature of things does not permit that the faculties imparted to a creature should not be necessarily confined within certain bounds.  The actions of creatures must be [41] necessarily proportioned to their essential state, and performed according to the character belonging to each machine; for according to the maxim of the philosophers, whatever is received is proportionate to the capacity of the subject that receives it.  We may therefore reject M. Leibniz’s hypothesis as being impossible, since it is liable to greater difficulties than that of the Cartesians, which makes beasts to be mere machines.  It puts a perpetual harmony between two beings, which do not act one upon another; whereas if servants were mere machines, and should punctually obey their masters’ command, it could not be said that they do it without a real action of their masters upon them; for their masters would speak words and make signs which would really shake and move the organs of the servants.