"Little by little the central point is abandoned, they no longer approach
it, and disappear in the sky, drawn by their fancy toward another point
which they will leave very soon.

"The thoughts of one who does not know how to gather them together and to
concentrate them are like these birds.

"They start from a central point, then spread out, at first without
getting far from this center, but soon they lose sight of it and fly
toward a totally different subject that a mental representation has
just produced.

"And this lasts until the moment when, in a sudden movement, the first
one is conscious of this wandering tendency.

"But it is often too late to bring back these wanderers to the initial
idea, for, in the course of their circuits, they have brushed against a
hundred others, which are confounded with the first, weaken it, and take
away its exact proportions.

"The great stumbling-block again is that of becoming lost in the details
whose multiplicity prevents us from discerning their complete function in
the act of practising deduction.

"It is better, in the case where our perception finds itself assailed by
the multitude of these details, to proceed by the process of elimination,
in order not to become involved in useless and lazy efforts.

"In this case we must act like a man who must determine the color of a