Mathew, Mary (1724–77), diarist, was daughter of the landowner Theobald Mathew (d. 1699) of Thurles Castle, Co. Tipperary, and his third wife, Catherine Nevill (d. 1742) of Leicestershire, England. Theobald Mathew had five children from his first marriage, one from his second, and four from his third. The family was well connected and wealthy; Mary never married but had independent means and was able to maintain her own establishment and move in society, relying on her brother as her financial executor. She lived for some years near Dublin, renting a house in Portmarnock where she entertained frequently between short visits to town and lengthy stays with relatives such as the Brownlows in Lurgan, Co. Armagh, and the Veseys in Abbeyleix, Queen's Co. For the year 1772–3 she kept a daily diary, and this, together with her meticulous accounts, which she kept for over twenty years, was published in 1991.
The diary reveals a comfortable life and an active social round of theatre, balls, assemblies, and card-playing. She was a keen gardener and a strong walker who enjoyed excellent health. She appears to have had few literary, cultural, political, or spiritual interests; although she frequently refers to God's will, she missed church services for trivial reasons and did not read the Bible regularly; nor did she read other books or evince any interest in art, music, or politics. Her chief preoccupations were the weather and how it affected her outdoor activities; her accounts, which she kept meticulously; and visiting her friends, particularly when they were unwell. Her charitable instinct was strong. Her bent was entirely practical, which does not make her the ideal diarist; she began her diary on 1 August 1772 with the express purpose of monitoring how she spent her time and trusting that she would benefit from the discipline of keeping it. She then seems to have regarded it as a rather disagreeable chore; she duly accounts for every single day but rarely writes more than a few lines and is seldom moved to confide intimate thoughts. It is with a great sense of relief that she reaches 31 July 1773 and concludes: ‘This day ends the year of the journal. I think my time is spent in so trifling a manner ‘tis not worth recording so here I end.’ She died four years later in 1777. Although there is little literary merit in the diary, it is useful historically for its rare glimpse at the life of an eighteenth-century Irishwoman.