Inventor of the difference engine
Charles Babbage is widely considered to be the father of the computer. The amazing thing is: he was able to concieve of a primitive computer (and a printer!) in 1822, yet engineering the materials to produce its parts would not be possible for decades, or so it was once thought until recently; his difference engine was finally realized as late as 1991, it worked perfectly, as did the printer - both engineered to his exact specifications. This proved, once and for all, that his difference engine would have worked, had the British Government not cut his funding in 1842.
"On two occasions I have been asked-'Pray, Mr.Babbage, if you put into the machine wrong figures, will the right answers come out?' In one case a member of the Upper, and in the other a member of the Lower House put this question. I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question."