Hum, interesting. I guess I always thought it was his because he actually developed very similar ideas in his essay &quot;In Praise of Idleness&quot;[1].<p>[1] <a href="http:&#x2F;&#x2F;www.zpub.com&#x2F;notes&#x2F;idle.html" rel="nofollow">http:&#x2F;&#x2F;www.zpub.com&#x2F;notes&#x2F;idle.html</a>