Blacklock was a Scottish poet and scholar. His father was a bricklayer, and his mother was the daughter of Mr Richard Rae, a cattle dealer.
He lost his sight as a result of smallpox when he was just six months old. At the age of 12, he began writing poetry, and due to the influence of some of his friends, he soon gained some reputation in Scotland and abroad as a blind poet with some promise.
By 1759 he had completed his theological studies, and he was licensed as a preacher in Dumfries, where he acquired a considerable reputation as a pulpit orator. He was appointed minister of Kirkcudbright, but was objected to by the parishioners on account of his blindness, and gave up the presentation on receiving an annuity. He later removed to Edinburgh, where he became a tutor, and in 1767 he was made a D.D. (Doctor of Divinity) from Marischal College in Aberdeen.
Blacklock's poems are mostly forgotten today, and his primary claim to fame is saving the life of poet Robert Burns by persuading him not to go to the West Indies, but to stay and publish his poems instead. The ship that Burns was supposed to travel with sank on its subsequent voyage with all lives lost. According to Corey Andrews in The Genius of Scotland: The Cultural Production of Robert Burns, 1785-1834, "[Burns wrote, in an autobiographical letter to John Moore,] that 'a letter from Dr. Blacklock overthrew all my schemes by rousing by poetic ambition.' He confesses that 'the Doctor belonged to a set a Critics for whose applause I had not even dared to hope'."
According to Chambers' Dictionary of Eminent Scotsmen (1872), "[i]t has been said of Dr Blacklock that 'he never lost a friend, nor made a foe;' and perhaps no literary man ever passed through life so perfectly free from envious feeling, and so entirely respected and beloved. His conversation was lively and entertaining; his wit was acknowledged, but it had no tinge of malice; his temper was gentle, his feelings warm—intense; his whole character was one to which may be applied the epithet amiable, without any qualification."
Blacklock came to visit Boswell for breakfast on August 17, 1773, during Samuel Johnson's stay in Edinburgh, shortly before Johnson and Boswell set out on their tour of Scotland. According to Boswell, in Journal of a Tour to the Hebrides, Sir William Forbes "brought with him Dr Blacklock, whom he introduced to Dr Johnson, who received him with a most humane complacency: “Dear Dr Blacklock, I am glad to see you!” Blacklock seemed to be much surprised when Dr Johnson said it was easier to him to write poetry than to compose his Dictionary. [...] Dr Blacklock spoke of scepticism in morals and religion with apparent uneasiness, as if he wished for more certainty."