The man of science, who, forgetting the limits of philosophical inquiry,
slides from these formulae and symbols into what is commonly understood
by materialism, seems to me to place himself on a level with the
mathematician, who should mistake the x's and y's with which he works
his problems for real entities--and with this further disadvantage, as
compared with the mathematician, that the blunders of the latter are of
no practical consequence, while the errors of systematic materialism may
paralyse the energies and destroy the beauty of a life.