Not sure it ever happened (happy to be contradicted), but what a good illustration as heard in this morning's sermon by Neil Green (my vicar).
Abraham Lincoln was once at a slave auction. A young girl was being sold, naked but for her shackles. Lincoln was so distressed by the thought of her being bought by any of the rabble present that he bid for her himself. As the price went up and up, Lincoln continued to outbid the rest and eventually he paid top dollar for her. The girl was brought to Abe, petrified of what a man who paid so much would want with her. Lincoln took off his great black cloak and clothed her saying 'You're free.'
The girl couldn't believe it. She said 'You mean I can go?'
He said 'Yes'.
'I can marry anyone I want?'
'I can work anywhere I like?'
'I can go anywhere I please?'
'Then,' she said, 'I will go with you.'