Not less than two hours a day should be devoted to exercise, and the weather should be little regarded.

I am an Epicurean. I consider the genuine (not the imputed) doctrines of Epicurus as containing everything rational in moral philosophy which Greek and Roman leave to us.

I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend.

Leave all the afternoon for exercise and recreation, which are as necessary as reading. I will rather say more necessary because health is worth more than learning.

I'm not against extracting a modest amount of wildlife out of the ocean for human consumption, but I am really concerned about the large-scale industrial fishing that engages in destructive practices like trawling and longlining.

The Environmental Control and Life Support System (ECLSS), which controls the living environment on shuttles and on the International Space Station, doesn't have the luxury of disposal: discharging trash into space has long been judged a bad idea.

Coal is the most carbon-intensive fuel available for electricity generation. The most urgent threat to climate policy is the scale of new investments in unabated coal-fired electricity generation still being planned.

Every day is Earth Day, and I vote we start investing in a secure climate future right now.