might easily
be shown, and would furnish a good illustration of that
important part of the Laws of Association, which may be
termed the Laws of Obliviscence.'

This chapter, on the Primary Qualities of Matter, controverts the
opinion of Sir W. Hamilton, that extension, as consisting of
co-existent _partes extra partes_, is immediately and necessarily
apprehended by our consciousness. It cites, as well as confirms, the
copious proof given by Professor Bain (in his work on the Senses and the
Intellect) that our conception of extension is derived from our muscular
sensibility: that our sensation of _muscular motion impeded_ constitutes
that of filled space: that our conception of extension, as an aggregate
of co-existent parts, arises from the sense of sight, which comprehends
a great number of parts in a succession so rapid as to be confounded
with simultaneity--and which not only becomes the symbol of muscular and
tactile succession, but even acquires such ascendancy as to supersede
both of them in our consciousness. Confirmation is here given to this
important doctrine, not merely by observations from Mr Mill himself, but
also from the very curious narrative, discovered and produced by Sir W.
Hamilton, out of a work of the German philosopher, Platner. Platner
instituted a careful examination of a man born blind, and ascertained
that this man did not conceive extension as an aggregate of simultaneous
parts, but as a series of sensations experienced or to be experienced in
succession--(pp. 232, 233). The case reported from Platner both
corroborates the theory of Professor Bain, and receives its proper
interpretation from that theory; while it is altogether adverse to the
doctrine of Sir W. Hamilton--as is also another case, which he cites
from Maine de Biran:--

'It gives a very favourable idea of Sir W. Hamilton's
sincerity and devotion to truth (remarks Mr Mill, p. 247),
that he should have drawn from obscurity, and made generally
known, two cases so unfavourable to his own opinions.'

We think this remark perfectly just; and we would point out besides, in
appreciating Sir W. Hamilton's merits, that his appetite for facts was
useful to philosophy, as well as his appetite for speculation. But the
person whose usefulness to philosophy we prefer to bring into the
foreground, is Platner himself. He spent three weeks in patient
examination of this blind man, and the tenor of his report