Berkeley, feeling a similar perplexity, is inclined to deny the truth of
infinitesimals in mathematics. Many difficulties arise in practical
religion from the impossibility of conceiving body and mind at once and in
adjusting their movements to one another. There is a border ground between
them which seems to belong to both; and there is as much difficulty in
conceiving the body without the soul as the soul without the body. To the
'either' and 'or' philosophy ('Everything is either A or not A') should at
least be added the clause 'or neither,' 'or both.' The double form makes
reflection easier and more conformable to experience, and also more
comprehensive. But in order to avoid paradox and the danger of giving
offence to the unmetaphysical part of mankind, we may speak of it as due to
the imperfection of language or the limitation of human faculties. It is
nevertheless a discovery which, in Platonic language, may be termed a 'most
gracious aid to thought.'

The doctrine of opposite moments of thought or of progression by
antagonism, further assists us in framing a scheme or system of the
sciences. The negation of one gives birth to another of them. The double
notions are the joints which hold them together. The simple is developed
into the complex, the complex returns again into the simple. Beginning
with the highest notion of mind or thought, we may descend by a series of
negations to the first generalizations of sense. Or again we may begin
with the simplest elements of sense and proceed upwards to the highest
being or thought. Metaphysic is the negation or absorption of physiology--
physiology of chemistry--chemistry of mechanical philosophy. Similarly in
mechanics, when we can no further go we arrive at chemistry--when chemistry
becomes organic we arrive at physiology: when we pass from the outward and
animal to the inward nature of man we arrive at moral and metaphysical
philosophy. These sciences have each of them their own methods and are
pursued independently of one another. But to the mind of the thinker they