内容简介：
Purchase one of 1st World Library's Classic Books and help support our free internet library of downloadable eBooks. Visit us online at www.1stWorldLibrary.ORG - - It is impossible to take a walk in the country with an average townsman - especially, perhaps, in April or May - without being amazed at the vast continent of his ignorance. It is impossible to take a walk in the country oneself without being amazed at the vast continent of one's own ignorance. Thousands of men and women live and die without knowing the difference between a beech and an elm, between the song of a thrush and the song of a blackbird. Probably in a modern city the man who can distinguish between a thrush's and a blackbird's song is the exception. It is not that we have not seen the birds. It is simply that we have not noticed them. We have been surrounded by birds all our lives, yet so feeble is our observation that many of us could not tell whether or not the chaffinch sings, or the colour of the cuckoo. We argue like small boys as to whether the cuckoo always sings as he flies or sometimes in the branches of a tree - whether Chapman drew on his fancy or his knowledge of nature in the lines: