Mackintosh fully accepts Hartley's doctrine of association. He even
criticises previous philosophers for not pushing it far enough. He
says that association, instead of merely combining a 'thought' and a
'feeling,' 'forms them into a new compound, in which the properties of
the component parts are no longer discoverable, and which may itself
become a substantive principle of human virtue.'[580] The question of
origin, therefore, is different from the question of nature. He
follows Hartley in tracing the development of various desires, and in
showing how the 'secondary desires' are gradually formed from the
primitive by transference to different objects.[581] We must start
from feelings which lie beneath any intellectual process, and thus the
judgment of utility is from the first secondary. We arrive at the
higher feelings which are 'as independent as if they were
underived,'[582] and yet, as happiness has been involved at every
stage as an end of each desire, it is no wonder that the ultimate
result should be to make the general happiness the end. The
coincidence, then, of the criterion with the end of the moral
sentiments is 'not arbitrary,' but arises necessarily from 'the laws
of human nature and the circumstances in which mankind are
placed.'[583] Hence we reach the doctrine which 'has escaped Hartley
as well as every other philosopher.'[584] That doctrine is that the
moral faculty is one; it is compound, indeed, in its origin; but
becomes an independent unit, which can no longer be resolved even in
thought into its constituent elements.

The doctrine approximates, it would seem, to Mill's; but was all the
more unpalatable to him on that account. The agreement implies
plagiarism, and the difference hopeless stupidity. To Mill Bentham was
the legitimate development of Hartley, while to Mackintosh Bentham
was the plausible perverter of Hartley. Mill regarded Mackintosh as a
sophist, whose aim was to mislead honest Utilitarians into the paths
of orthodoxy, and who also ignored the merits of Mill himself. 'It was
Mr. Mill,' he says, 'who first made known the great importance of the
principle of the indissoluble association';[585] 'Mr. Mill' who had
taken up Hartley's speculations and 'prosecuted the inquiry to its
end';[586] 'Mr. Mill' who explained affections and motives and
dispositions;[587] and 'Mr. Mill' who had cleared up mistakes about
classification which 'had done more to perpetuate darkness on the
subject of