12 ZSTHETIO RELATIONS OF BIRDS. 
share its emotions as you learn the significance of its 
notes. No one can listen to the song of the Mockingbird 
without being in some way affected; but in how many 
hearts does the tink of the night-flying Bobolink find a 
response? I never hear it without wishing the brave 
little traveler Godspeed on his long journey. 
As time passes you will find that the songs of birds 
bring a constantly increasing pleasure. This is the result 
of association. The places and people that make our 
world are ever changing; the present slips from us with 
growing rapidity, but the birds are ever with us. 
The Robin singing so cheerily outside my window 
sings not for himself alone, but for hundreds of Robins I 
have known at other times and places. His song recalls 
a March evening, warm with the promise of spring; May 
mornings, when all the world seemed to ring with the 
voices of birds; June days, when cherries were ripening ; 
the winter sunlit forests of Florida, and even the snow- 
capped summit of glorious Popocatepetl. And so it is 
with other birds. We may, it is true, have known them 
for years, but they have not changed, and their familiar 
notes and appearance encourage the pleasant self-delusion 
that we too are the same. 
The slender saplings of earlier years now give wide- 
spreading shade, the scrubby pasture lot has become a 
dense woodland. Boyhood’s friends are boys no longer, 
and, worst of all, there has appeared another generation 
of boys whose présence is discouraging proof that for us 
youth has past. Then some May morning we hear the 
Wood Thrush sing. Has he, too, changed? Not one 
note, and as his silvery voice rings through the woods 
we are young again. No fountain of youth could be 
more potent. A hundred incidents of the long ago be- 
come as real as those of yesterday. And here we have 
the secret of youth in age which every venerable natural- 
