him to become reconciled to it.

I put into a room various kinds of wild birds, which had been taken in
nets after they were full grown. The window, which looked upon a garden,
was unglazed, and closed by a wire netting, through which the outer air
entered and was constantly renewed. I placed in the middle of the room a
pot containing a shrub of some size, on which the birds used to perch.
Since they had been reared in the open air they were certainly
accustomed to the wind, and to the way in which it moves trees and
branches, so that they were not alarmed by a phenomenon which they
recognized from experience. I fastened a cord to the head of the shrub
which I passed through a hole in the door, making another to look
through, and in this way I moved it to and fro as the wind might have
done. One day when there was a high wind which could be heard in the
room, and when the current of air through the window was perceptible, I
tried the experiment when the conditions of resemblance were perfect.
And yet when the violent movement and oscillation of the shrub was
combined with the noise of the wind, the frightened birds all fluttered
about, and after repeating the movement, and then allowing it to
subside, they kept away from the shrub and did not dare to settle on it.

At another time, aided by an ingenious young friend, I constructed a toy
windmill, of which the vanes were moved by weights. I placed this toy in
a cage, so arranged that its motions could be regulated from the
outside, and I put into the cage a sparrow, which had been taken from
the nest, and which consequently had no experience of the external
world. Much patience was needed, since the toy required careful
adjustment and was easily thrown out of gear, but I managed it at last.
The sparrow pecked at the little mill as soon as he was put into the
cage, and he grew up accustomed to its motions. I then took the sparrow