Of course neither the robin nor his mate had ever heard of the champion wrestler, Bob Haworth, and his exercises for making the muscles stand out like lumps.

Robins are not like human beings; their muscles are always exercised from the first and so they develop themselves in a natural manner.

If you have to fly about to find every meal you eat, your muscles do not become atrophied (atrophied means wasted away through want of use).
When the boy was walking and running about and digging and weeding like the others, the nest in the corner was brooded over by a great peace and content.

Fears for the Eggs became things of the past.

Knowing that your Eggs were as safe as if they were locked in a bank vault and the fact that you could watch so many curious things going on made setting a most entertaining occupation.