Never heard of this quote, but I could certainly use a large dose of tact as defined above! The quote seems to be due to an advertising executive though, Howard W. Newton, not Isaac Newton [1].
[^1]: My idea of Isaac Newton comes from Stephenson's novel. But I trust that Mr Stephenson's research because it aligns with Newton's other quotes (i.e. "standing in the shoulder of giants" is nice but he's calling another man a moron, eloquently) and the his relationship with Leibniz wasn't the one I would expect.
Advertisers probably understand people better than physicists.