One does not let mysteries out of one’s hand when one has once grasped them. The secrets of the wealthy are sponges of gold
 Victor Hugo, Les Misérables (1862). copy citation

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Author Victor Hugo
Source Les Misérables
Topic mystery secret
Date 1862
Language English
Reference
Note Translation by Isabel F. Hapgood in 1887
Weblink http://www.gutenberg.org/files/135/135-h/135-h.htm

Context

“He would have given fifteen thousand francs. But I shall overtake him.” And then, that bundle of clothes prepared beforehand for the child; all that was singular; many mysteries lay concealed under it. One does not let mysteries out of one’s hand when one has once grasped them. The secrets of the wealthy are sponges of gold; one must know how to subject them to pressure. All these thoughts whirled through his brain. “I am an animal,” said he. When one leaves Montfermeil and reaches the turn which the road takes that runs to Livry, it can be seen stretching out before one to a great distance across the plateau.” source