A source of Barret's earliest landscape paintings came from the re-working of engravings of classical Italianate scenes of artists such as Claude Lorrain. A pair of paintings sold in 2013, came from the collection of the Rev. Samuel Madden (1686–1765). Madden established a series of prizes at Trinity College, Dublin, to reward agricultural and artistic enterprise, designed an important landscape garden on the shores of Lough Erne, founded the Dublin (later Royal) Society, and left an important collection of 17th- and 18th-century Italian pictures to Trinity College. These two paintings were based on engravings of two paintings by Claude Lorrain. One of these is after "Landscape with a rural dance", which belonged to the Duke of Kingston. The second is a "Landscape with Argus guarding Io", purchased by the first Earl of Leicester and still at Holkham Hall, in which Barret has reversed the image in his painting. There are a number of other Italianate paintings showing ruins which Barret probably painted before developing his series of Irish landscapes.