Gravity is only the bark of wisdom's tree, but it preserves it.

I saw them; there is nothing beautiful about them, just that they are a little higher than the others.
Referring to one of the oldest and loveliest groves of redwoods, showing insensitivity to their magnificence.

I think, too, that we've got to recognize that where the preservation of a natural resource like the redwoods is concerned, that there is a common sense limit. I mean, if you've looked at a hundred thousand acres or so of trees—you know, a tree is a tree, how many more do you need to look at?
Opposing expansion of Redwood National Park.

Sir Edward has calculated that quick-growing Indian eucalyptus trees have a yield of nine and one-quarter tons of wood an acre a year. As the wood contains 0.8 per cent of the solar energy reaching the ground in the tropics in the form of heat, Sir Edward has suggested that in theory eucalyptus forests could provide a perpetual source of fuel. He has said that by rotational tree planting and felling, a forest of twenty kilometers square would enable a wood consuming power station to provide 10,000 kilowatts of power.