A very short story by Baudelaire.  

As we were walking away from a tobacconist’s, my friend carefully sorted out his change: into his left vest pocket he slipped the small gold coins, into his right vest pocket the small silver coins; into the left pocket of his pants, a handful of large copper coins, and finally into his right pant’s pocket, a two franc silver piece he had examined with particular attention.

“A singular and meticulous division!,” I said to myself.

We encountered a poor man who tremblingly held out his hat to us. — I know nothing more disquieting than the mute eloquence of those supplicating eyes, which contain at one and the same time so much humility and so many reproaches, at least for the sensitive man who knows how to read them.  He finds something approaching these depths of complicated emotion in the tearful eyes of dogs being beaten.

My friend’s offering was much larger than my own, and I said to him: “You are right: next to the pleasure of being astonished, there is none greater than causing surprise.”  “It was the counterfeit coin,” he replied tranquilly, as if to justify his prodigality.

But into my miserable brain, always missing the obvious (what a tiresome faculty nature made me a gift of!), entered suddenly the idea that such conduct on the part of my friend was only excusable on the grounds of a desire to create an event in the life of that poor devil, perhaps even to learn the diverse consequences, whether deadly or otherwise, that a counterfeit coin might produce in the hands of a beggar.  Might it not be converted into real coins?  Might it not also lead him into prison?  A publican or a baker might, for example, have him arrested as a counterfeiter or as a passer of counterfeit coins.  But the counterfeit coin might also just as well serve as the seed for several day’s wealth, in the hands of a poor, small-scale speculator.  And so my fancy played itself out, lending wings to the spirit of my friend and drawing all possible deductions from all possible hypotheses.

But he brusquely broke my reverie by repeating my very words: “Yes, you are right: there is no pleasure sweeter than surprising a man by giving him more than he had hoped for.”

I gazed into the whites of his eyes, and I was appalled to see that his eyes were shining with an incontestable candor.  I then saw clearly that he had wanted to both perform a charitable act and make a good deal at the same time — to gain forty sous and the heart of God; to get into paradise economically; finally, to earn for free the badge of a charitable man.  I might almost have pardoned him for the desire for criminal enjoyment of which I had just recently supposed him capable.  I would have found it curious and singular that he amused himself by compromising the poor, but I could never pardon him for the ineptness of this calculation.  One is never excused for being evil, but there is some merit in knowing that one is — and the most irreparable of vices is to do evil through stupidity.