the FDA staff surprised the researchers by asking them to expand their focus and ambition: to test whether psilocybin could be used to treat the much larger and more pressing problem of depression in the general population. As the regulators saw it, the data contained a strong enough “signal” that psilocybin could relieve depression; it would be a shame not to test the proposition, given the enormity of the need and the limitations of the therapies now available.

