His attention is flowing, always in transition, leaping from "it to that," with superb agility and restlessness.

But the exercise it gains from its movements is its only reward.

Its acquisitions are slender in the extreme.

It illustrates, on the mental plane, the truth of the "rolling stone." It corresponds, as a mental character, to the muscular restlessness which the same type of child shows in the earlier period previously spoken of.
The psychological explanation of this "fluid attention" is more or less plain, but I can not take space to expound it.

Suffice it to say that the attention is itself, probably, in its brain seat, a matter of the motor centres; its physical seat both "gives and takes" in co-operation with the processes which shed energy out into the muscles.