I found the quote below in my copy of Death and Life of Great American Cities by Jane Jacobs (price 3s 6d). I say 'found' because I haven't looked at the book for some time and didn't remember the quote:
Until lately the best thing that I was able to think of in favour of civilization, apart from blind acceptance of the order of the universe, was that it made possible the artist, the poet, the philosopher, and the man of science. But I think that is not the greatest thing. Now I believe that the greatest thing is a matter that comes directly home to us all. When it is said that we are too much occupied with the means of living to live, I answer that the chief worth of civilization is just that it makes the means of living more complex; that it calls for great and combined intellectual efforts, instead of simple, uncoordinated ones, in order that the crowd may be fed and clothed and housed and moved from place to place. Because more complex and intense intellectual efforts mean a fuller and richer life. They mean more life. Life is an end in itself, and the only question as to whether it is worth living is whether you have enough of it.
I will add but a word. We are all very near despair. The sheathing that floats us over its waves is compounded of hope, faith in the unexplainable worth and sure issue of effort, and the deep, sub-conscious content which comes from the exercise of our powers.
OLIVER WENDELL HOLMES, JR
I like this - it is an elegant argument in favour of the 'examined life' .
I have to confess I have never knowingly read anything by Wendell Holmes, although the name is known to me. I am sure that some will be horrified but I look on that gap as a prime example of what he is talking about - another opportunity for a fuller and richer life.
Mrs Jacobs does not identify the source of this quotation as far as I can tell, and I haven't found a phrase from it which turns up anything on Google. What does turn up suggests that most posters, like me got it from Mrs Jacobs. Any erudite reader out there with an idea of the source?
UPDATE: My ignorance is compounded - the Oliver Wendell Holmes I knew about (vaguely) - a doctor, writer and poet- is actually the father of this Oliver Wendell Holmes - a judge and writer.