Graduation time brings out the inspirational quote. One quotation keeps showing up, disasterous advice and a misquotation. Before getting to the ethics problem, as a public service, let me suggest three truths about citing famous people:
First, relying on quotation sites on the ‘Net is dangerous. Check the original text.
Once while reading Sarah Palin, I discovered she had at least three quotations (including one from Plato) that were wrong. A quick Google showed a quote site that had all the errors.
Second, if the citation does not include a text reference and Google does not show the text it is from, assume it is spurious.
Everyone gets something wrong, sometime. I relied on a book that said Alfred Wallace was a Lord: wrong. If you cite badly, just be sorry, correct, and hope your critic can let it go!
Third, Shakespeare and Plato are very dangerous to cite as they don’t always agree with their characters.