Quotations and Literature Forum

Does anybody know the source of the following Santayana quote? "That life is worth living is the most necessary of assumptions, and, were it not assumed, the most impossible of conclusions."

-DJ

This webpage states the following source:

That life is worth living is the most necessary of assumptions, and, were it not assumed, the most impossible of conclusions.
~George Santayana (1863-1952)
The Life of Reason, 1905-1906
Volume I, "Reason in Common Sense"
http://www.evcom.net/~tourette/quotations/L.htm

The person on this webpage agrees:

That life is worth living is the most necessary of assumptions and, were it not assumed, the most impossible of conclusions.
-- George Santayana, "Reason in Common Sense"
http://www.ahc.umn.edu/NewsAlert/Sep99/ ... /34753.htm
http://www.theindependent.com/stories/0 ... lly29.html