From Garrett Reisman:

My experience was quite different from Mr. Shatner's and different from most astronauts, for that matter. I did not find the view of the Earth out the window to be in any way depressing. The Earth was beautiful - especially the Eastern part of Africa and all of Australia, both of which had magnificent red and brown hues that looked more like Mars to me than Earth.

But I did not really experience the 'overview effect' often described by astronauts as the realization that we are all one humanity sharing the same home and breathing the same atmosphere. That all the things that divide us: nationality, religion, race, gender, politics, etc. are so much less important than these things that we all have in common.

These observations are all true of course, but perhaps I wasn't suddenly struck by them because I knew this before I went to space. The fact that we are all created equal should be self-evident. You shouldn't have to strap yourself into a rocket to understand this.