In 1926, Thomas Edison sent a brief letter to one of his employees congratulating him on his ideas but warning him about the road ahead.
A transcript of the letter is below:
My dear Mr. Emmet:-
I want to thank you for your letter of the 23rd, with its enclosure, and at the same time to extend my congratulations to you on the successful outcome of your ideas.
The worst is to come, for it takes about seven years to convert the average man to the acceptance of a solved problem.
With all good wishes to you, I remain
Yours very truly
Thos. A. Edison