"We are tilted. This is the first thing to understand. The axis of the earth's rotation is not perpendicular to the plane of the earth's orbit round the sun. It is tilted at about 23.5 degrees. The tilt means that the Northern and Southern Hemispheres are angled towards the sun for part of the year, and away from the sun for another part of the year. We have seasons. Climates turn welcoming and inhospitable in regular sequence.  Food supplies dwindle in one place even as they burgeon in another.  All creatures must adapt to these cycles if they are to survive.  Migration is a way of coping with the tilt."

William Fiennes.  The Snow Geese: A Story of Home (New York: Random House, 2003): 12-13.

April Sentiments 

Nikon FE2, 50mm