A machine that never got built still sparked a vision of what computers might one day do.
In the 1830s, mathematician Charles Babbage designed the Analytical Engine, a steam-powered machine intended to carry out many kinds of calculation. It remained unfinished. Ada Lovelace, who had met Babbage as a young woman, published an account of the design in 1843, adding extensive notes of her own.
Lovelace described how punched cards might direct the machine and explored how it could manipulate symbols as well as numbers—if those symbols could be represented by rules. Her Bernoulli-number table is often called the first computer program, though scholars note it was an execution trace, not punched-card code. The Science Museum describes her as interpreting and publicizing Babbage's design; the Engine itself was never completed in her lifetime.
Her striking insight was not that a machine had already composed music or thought for itself, but that a programmable machine might work with patterns beyond arithmetic.