twin brother of T. Vaughan, was born at Newton‐upon‐Usk, Breconshire. His wooing of his first wife Catherine is apparently recalled in the poem ‘Upon the Priory Grove’ printed in Poems with the Tenth Satire of Juvenal Englished (1646), his first collection. His second, Olor Iscanus (‘The Swan of Usk’), has a dedication bearing the date 1647, but was not published till 1651. The poems in these two volumes are almost wholly secular and there is little in them that anticipates the great religious poetry of Vaughan's next volume, Silex Scintillans (1650). Further devotional works followed: The Mount of Olives, or Solitary Devotions (1652), Flores Solitudinis (1654), and the second edition (with a second part) of Silex Scintillans (1655), in which he acknowledges his debt to G. Herbert. Vaughan's first wife having died, he married her younger sister Elizabeth, probably in 1655. They had a son, Henry, and three daughters. According to a letter he sent to Aubrey in 1673 he had by that date been practising physic ‘for many years with good success’.
Vaughan's religious poetry is uneven, but its best moments, like the start of ‘The World’ (‘I saw Eternity the other night’), are wholly distinctive, and have prevailed with critics to class him as a ‘mystic’. He was seized with the idea of childish innocence, and the child's recollections of prenatal glory. He writes, in ‘The Retreat’, of his own ‘Angel‐infancy’, when he would muse on clouds and flowers and see in them ‘Some shadows of eternity’. Vaughan's fascination with hermeticism, and particularly with the idea of sympathetic bonds uniting microcosm and macrocosm, is clear in his poems, many of which share ideas and even phrases with his brother Thomas's treatises. On the title pages of Olor Iscanus and Silex Scintillans Vaughan calls himself a ‘Silurist’, presumably because his native Brecon was anciently inhabited by the British tribe of Silures.
His brother Thomas died in 1666, and in 1678 Thalia Rediviva, containing poems by both twins, was published. His later life was marred by litigious feuds between his first and second families.