It started with a problem.
Dan Bricklin was a first-year student at Harvard Business School in the spring of 1978 when he watched a professor work through a complex financial model on a blackboard. When one number changed, the professor had to erase and recalculate each dependent figure by hand. Bricklin imagined a program that would do this automatically. He developed the concept with Bob Frankston, whom he had met at MIT. They formed Software Arts and wrote the program in the winter of 1978 to 1979. VisiCalc was unveiled at the National Computer Conference in New York in June 1979 and released for the Apple II. It was the first spreadsheet program for a personal computer.
Historical sources below ↓Then something changed.
VisiCalc changed what a personal computer was useful for to people who were not programmers. The Harvard Gazette account describes how it turned twenty hours of financial recalculation into fifteen minutes. More significantly, it made sensitivity analysis accessible: a businessperson could now ask 'what if sales drop 10 percent?' and see the answer immediately, without specialized staff. This changed how business planning was done. Decisions that previously required a financial analyst could be tested by the person making the decision. The spreadsheet became the dominant tool for business modeling, budgeting, and analysis, a position it has held for more than four decades.
What a builder can learn.
Our interpretation: VisiCalc's value was not the calculation — businesses could always hire someone to calculate. Its value was immediacy. When a decision-maker could test assumptions themselves, the gap between question and answer collapsed. This changed not just speed but the nature of the question asked: people asked questions they would not have bothered an analyst with. For a business builder, tools that let decision-makers test their own assumptions without specialist help change the quality of decisions made under uncertainty.
A door still open.
A hypothesis worth testing: if the owner of a small business spent two hours building a simple model of their key cost drivers and revenue levers in a spreadsheet — without needing it to be perfectly accurate — would they make at least one different decision in the following month than they would have without that model?
What assumption drives most of your business decisions that you have never actually tested with numbers?
Follow the evidence.
History is sourced below. Business lessons are editorial interpretations; future possibilities are questions to test, not predictions.
Prepared from primary-source histories. First edition: 25 Sept 2026.