LESLEY, ALEXANDER. - Jesuit, liturgist, born in the county of Aberdeen (Scotland) on 7 Nov. 1694, died in Rome on 27 March 1758. He taught successively at Sora and Ancona, then Greek at the Collegio Romano and philosophy at the Collegio Illirico of Loreto. In 1728 he was sent to Scotland. In 1734 he is found again in Italy, first as professor at Tivoli, then at the Collegio Scozzese, where he was also prefect of studies. From 1746 to 1749 he taught moral theology at the Collegio Inglese.
In 1749 he had been associated with Fr. Manuel de Azevedo for the publication of the Thesaurus liturgicus, a work announced in 13 folio volumes. Of this collection L. published in Rome, in 1755, the Missale mixtum secundum Regulam beati Isidori dictum Mozarabeo, a reprint of the Mozarabic Missal published at Toledo in 1500 by order of Cardinal Ximenes, enriched by an important preface and valuable notes. An identical work prepared for the Mozarabic Breviary, as well as many other dissertations of a numismatic and epigraphic character, remain in manuscript.