“He who labors diligently need never despair; for all things are accomplished by diligence and labor.”

In a very narrow scope of hindsight on specific cases, an accurate observation. Here, another observation comes to mind: "The definition of insanity is doing the same thing over and over and expecting different results." Also, the diligent labors of politicians who continue to borrow to get out of debt need never despair, the Federal Reserve can always print more ;-( 

Diligence and labor, and diligent labor, are not, necessarily, means of deliverance from desperation.

The Fall has rendered life and labor dualistic, occasionally sweet and commonly bitter.

Ah yes, the Art of Folly.  ;-)  Yes, intent is integral — what are we laboring for?  We are in a constant process of growing, and our wants grow with us.  Do we ever wise up?  None-the-less, honest, diligent labor is honorable work, even if the laborer is narrow-sighted and even foolish.  The intent is as important as the labor, but intent without diligent labor is irresponsible and furthers delusion.

The hands of the diligent lend themselves to prosperity. to what degree you prosper another, should be a choice of freewill. If intent was just, in harmony with freewill association, property and person would have remained secure. Stalin's demise, socialism in the city, capitalism in the rural country. Yet he destroyed the lives of millions due to his bias against capitalism. Now, this Nation finds itself at odds with old world socialist, who seek to destroy the remains of Independence, enslaving all to the fancy and whims of corrupt elites.