“On two occasions, I have been asked [by members of Parliament], ‘Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’…I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question.”
— Charles Babbage, Passages from the Life of a Philosopher (1864), p. 67

Computers. When designed properly, they do precisely what they are told. They do not interpret, they need to be explicitly instructed on what exactly to do. However, when you get them going, they give you incredible capabilities. During WW2, people would have sacrificed armies to obtain the computing power in your cell phone. Even a simple flip phone has more power than all the computers in existence at the time. Charles Babbage could have revolutionized history, had manufacturing been up to the task — William Gibson’s novel The Difference Engine posits just such a future. (It was the beginning of the Steampunk genre)