Chance favors the prepared mind

“Chance favors the prepared mind” is the maxim that links Gene Johnson’s unsuccessful search for Marburg virus at Kitum Cave to the sudden outbreak response near Washington. At first it accompanies the disappointment of finding no virus; later, it gives meaning to the African field gear he had kept ready and to the experience he could bring to a new emergency.

Attribution and Meaning

Johnson recalls the saying as a remark by Louis Pasteur, whom the book notes developed vaccines for anthrax and rabies. In the passages where it recurs, the maxim is not a promise that preparation will prevent failure. It expresses a more practical faith: knowledge, experience, and equipment acquired without an immediate payoff may become useful when circumstances change.

After the Kitum Cave Expedition

The saying follows a dispiriting search. The expedition’s sentinel animals remained healthy, and tests of blood and tissue from other animals, insects, birds, Masai people, and cattle showed no sign of Marburg virus. Johnson was so discouraged by the negative findings that he never published an account of the expedition. What he could say with certainty was that Marburg lived in the shadow of Mount Elgon.

The search had also left Johnson with experience and protective equipment that he did not discard. He stored his African gear in olive-drab military trunks and trailers behind buildings, padlocking it away because he did not want anyone else to use or remove it. He wanted to be able to load it onto an airplane at a moment’s notice if Marburg or Ebola surfaced again in Africa. The maxim gives that otherwise private stockpile a purpose: apparent failure had not made the preparation worthless.

The Saying Returns in Washington

When Ebola appeared in a monkey house near Washington, Johnson remembered the maxim. He had spent almost ten years hunting Ebola and Marburg in Africa with little success, and his anxiety about exposure had persisted in nightmares of liquid leaking through pinholes in a protective suit. Now the crisis called for the very experience and equipment he had preserved.

Johnson recognized practical similarities between the monkey house and Kitum Cave: both were enclosed spaces with stagnant air, failed air-handling systems, and animal waste. He reasoned that teams would need a staging area and a gray area functioning as an air lock, with a chemical shower, to move safely in and out. The saying thus returns not as an abstract tribute to foresight but as a prompt for action: a previous expedition, even one that found no virus, had helped prepare Johnson to confront a new danger.