in 1824, moved to Hawley, Massachusetts, to begin his practice, and then served two months in the Worcester County jail for illegal dissection.

A year later, the town's new minister, Mason Grosvenor, began a campaign against "infidelity and licentiousness," targeting Knowlton as its source.

Knowlton had written a little book entitled, The Fruits of Philosophy, or the Private Companion of Young Married People, and had been showing it to his patients.

Abner Kneeland printed a second edition of Fruits of Philosophy in Boston in 1832, allowing it a wider circulation than the few closely guarded copies Knowlton had been lending to patients.

This led to Knowlton's imprisonment in Cambridge at “hard labor” for three months, and was a central issue in Kneeland's blasphemy trial in 1838.

Reverend Grosvenor filed a complaint against Knowlton in Franklin County, but after two juries failed to convict him, the charges were dropped.

Twenty-seven years later, Charles Bradlaugh and Annie Besant were tried in London for publishing Knowlton's Fruits of Philosophy there.