y extended object the _adequate_ mental picture must
have all the extension of the object itself. The difference between
objective and subjective extension is one of relation to a context
solely. In the mind the various extents maintain no necessarily stubborn
order relatively to each other, while in the physical world they bound
each other stably, and, added together, make the great enveloping Unit
which we believe in and call real Space. As 'outer,' they carry
themselves adversely, so to speak, to one another, exclude one another
and maintain their distances; while, as 'inner,' their order is loose,
and they form a _durcheinander_ in which unity is lost.[21] But to argue
from this that inner experience is absolutely inextensive seems to me
little short of absurd. The two worlds differ, not by the presence or
absence of extension, but by the relations of the extensions which in
both worlds exist.

Does not this case of extension now put us on the track of truth in the
case of other qualities? It does; and I am surprised that the facts
should not have been noticed long ago. Why, for example, do we call a
fire hot, and water wet, and yet refuse to say that our mental state,
when it is 'of' these objects, is either wet or hot? 'Intentionally,' at
any rate, and when the mental state is a vivid image, hotness and
wetness are in it just as much as they are in the physical experience.
The reason is this, that, as the general chaos of all our experiences
gets sifted, we find that there are some fires that will always burn
sticks and always warm our bodies, and that there are some waters that
will always put out fires; while there are other fires and waters that
will not act at all. The general group of experiences that _act_, that
do not only possess their natures intrinsically, but wear them
adjectively and energetically, turning them against one another, comes
inevitably to be contrasted with the group whose members, having
identically the same natures, fail to manifest them in the 'energetic'
way.[22] I make for myself now an experience of blazing fire; I place it
near my body; but it does not warm me in the least. I lay a stick upon
it, and the stick either burns or remains green, as I please. I call up
water, and pour it on the fire, and absolutely no difference ensues. I
account for all such facts by calling this whole train of experiences
unreal, a mental train. Mental fire is what won't burn real sticks;
mental water i