“I did not, however, aim at gaining his favor by paying any servile respect to him, but after some time took this other method. Having heard that he had in his library a certain very scarce and curious book, I wrote a note to him expressing my desire of perusing that book and requesting that he would do me the favor of lending it to me for a few days. He sent it immediately; and I returned it in about a week expressing strongly the sense of the favor. When we next met in the House he spoke to me, which he had never done before, and with great civility; and he ever after manifested a readiness to serve me on all occasions, so that we became great friends, and our friendship continued until his death. This is another instance of the truth of an old maxim I had learned, which says: ‘He that has once done you a kindness will be more ready to do you another than he whom you yourself have obliged.’” – Benjamin Franklin, The Authobiography of Benjamin Franklin

Looks like giving things away for free isn’t the only way to scrape up some influence.