ther hand
Plotinus sometimes speaks of it as of a _discourse_. More generally, the
relation that we establish in the present chapter between "extension"
and "detension" resembles in some aspects that which Plotinus supposes
(some developments of which must have inspired M. Ravaisson) when he
makes extension not indeed an inversion of original Being, but an
enfeeblement of its essence, one of the last stages of the procession,
(see in particular, _Enn._ IV. iii. 9-11, and III. vi. 17-18). Yet
ancient philosophy did not see what consequences would result from this
for mathematics, for Plotinus, like Plato, erected mathematical essences
into absolute realities. Above all, it suffered itself to be deceived by
the purely superficial analogy of duration with extension. It treated
the one as it treated the other, regarding change as a degradation of
immutability, the sensible as a fall from the intelligible. Whence, as
we shall show in the next chapter, a philosophy which fails to recognize
the real function and scope of the intellect.]

[Footnote 81: Bastian, _The Brain as an Organ of the Mind_, pp. 214-16.]

[Footnote 82: We have dwelt on this point in a former work. See the
_Essai sur les donnees immediates de la conscience_, Paris, 1889, pp.
155-160.]

[Footnote 83: _Op. cit._ chaps. i. and ii. _passim_.]

[Footnote 84: Cf. especially the profound studies of M. Ed. Le Roy in
the _Revue de metaph. et de morale_.]

[Footnote 85: _Matiere et memoire_, chapters iii. and iv.]

[Footnote 86: See in particular, _Phys._, iv. 215 a 2; v. 230 b 12;
viii. 255 a 2; and _De Caelo_, iv. 1-5; ii. 296 b 27; iv. 308 a 34.]

[Footnote 87: _De Caelo_, iv. 310 a 34 [Greek: to d' eis ton autou topon
pherethai hekaoton to eis to autou eidos esti pheresthai].]

[Footnote 88: On these differences of quality see the work of Duhem,
_L'Evolution de la mecanique_, Paris, 1905, pp. 197 ff.]

[Footnote 89: Boltzmann, _Vorlesungen uber Gastheorie_, Leipzig, 1898,
pp. 253 ff.]

[Footnote 90: In a book rich in facts and in ideas (_La Dissolution
opposee a l'evolution_, Paris, 1899), M. Andre Lalande shows us
everything going towards death, in spite of the momentary resistance
which organisms seem to oppose.--But, even from the side of unorganized
matter, have we the right to extend to the entire universe
considerations drawn from the present state of our solar system? Beside
the worlds which are dying, there are without doubt worlds that are
b