We are way less aware of nature than we used to be. We're out gardening for a couple of hours a day, certainly, but we don't (mostly) live in the open, it's not our workplace as it was for former generations; those of us for whom it is encounter it through the glass walls of a tractor, the sounds drowned out by motors.

We don't walk from place to place at all hours of day and night; we don't drive cattle on foot to the market; we don't find our food by trapping and fishing.

Children, especially, live indoor lives - incredibly so compared even to my childhood, much less when compared to 100 years ago, when most of the songs we're considering were written. I don't know when I last saw a kid up a tree - when I was a child most of my time seemed to be spent dangling dangerously out of high branches, cycling, swimming, running, skipping, playing games of pretend necessitating much outdoor activity.

And so we haven't noticed - as Rachel Carson foretold - the gradual decline in bees and butterflies and animals; the spring has become silent for many of us, and it's happened while we were indoors.

One result for humans is the worldwise increase in short sight; if children aren't outdoors for a great deal of time during the two or three years preceding puberty, their eyeballs lock into the short focus that is myopia.

Other results are worldwide epidemics of diabetes, heart disease, hypertension, cancer, depression and possibly even psychosis.