His father was a Protestant refugee from Beaufort, Provence; he settled in the Dutch Republic and became minister of the Walloon church at Montfoort, and subsequently catechist at The Hague, but was dismissed from his benefices and excommunicated by synods at Kampen and The Hague in 1730 for maintaining, in a letter on ‘The Mystery of the Trinity’ to De la Chappelle, that the Son and Holy Spirit are two finite beings created by God, and at a certain time united to him.
After ineffectual protest against the decision of the synods, the elder Maty sought refuge in England, but was unable to find patronage there, and had to return to The Hague, whence his enemies drove him to Leiden.
He lived in Leiden with his brother Charles Maty, compiler of a Dictionnaire géographique universel (1701 and 1723, Amsterdam), in 1751, being then seventy years of age.
Matthew was entered at Leiden University on 31 March 1732, and graduated PhD in 1740, the subject for his inaugural dissertation (which shows Montesquieu's influence) being ‘Custom.’ A French version of the Latin original, greatly modified, appeared at Utrecht in 1741 under the title ‘Essai sur l'Usage,’ and attracted some attention.
He frequented a club which numbered Drs James Parsons, Peter Templeman, William Watson, and John Fothergill among its members, and met every fortnight in St Paul's Churchyard, but soon began to devote his energies to literature.
He had been elected Fellow of the Royal Society on 19 December 1751, and in 1753, on the establishment of the British Museum, he was nominated, together with James Empson, an under-librarian, the appointment being confirmed in June 1756.