 In addition to a short biographical entry in the Oxford Dictionary of National Biography (Perkins 2004), the main source of information about Shepherd’s life is a family memoire written by her daughter and published for private use (Brandreath 1886). Shepherd was born in Barnbougle Castle on the Primrose family estate overlooking the Firth of Forth. She lived mainly there until her marriage in 1808. While her brothers were sent to university, she and her sisters were educated at home by private tutor. Her daughter reports that in addition to teaching them Latin, geography, mathematics, and history, he discussed many works on the foundation of the truth of things. His pupils were encouraged to pursue whatever subjects interested them. Mary is said to have written volumes of metaphysical essays many of them critical of Hume and the Unitarian doctrines of Joseph Priestly (Brandreath 1886: 28–9). In a letter to Charles Babbage, she recalls having had an interest in the reasoning used in proofs of mathematical theorems and exposing errors of reasoning in a wide range of authors (quoted in McRobert 2000: vi). Her published essays were written sometime later.