He was born at Grantham. Both his parents were Calvinists but he himself "could never swallow that hard doctrine." In 1631 he entered Christ's College, Cambridge, at about the time John Milton was leaving it. He devoted himself to the study of philosophy, and for a time adopted a scepticism, from which he was turned by the study of the "Platonic writers." He was fascinated especially by Neoplatonism, and this fascination never left him. The Theologia germanica also exerted a permanent influence over him.
He took his BA in 1635, his MA in 1639, and immediately afterwards became a fellow of his college, turning down all other positions that were offered. He would not accept the mastership of his college, to which, it is understood, he would have been preferred in 1654, when Ralph Cudworth was appointed. In 1675, he finally accepted a prebend in Gloucester Cathedral, but only to resign it in favour of his friend Dr Edward Fowler, afterwards bishop of Gloucester.
More taught many notable pupils, but the most interesting was a young lady, probably a sister of Lord Finch, subsequently Earl of Nottingham, a well-known statesman of the Restoration. She later became Lady Conway, and at her country seat at Ragley in Warwickshire More would spend "a considerable part of his time." She and her husband both appreciated him, and amidst the woods of this retreat he wrote several of his books. The spiritual enthusiasm of Lady Conway was a considerable factor in some of More's speculations, even though she at length joined the Quakers. She became the friend not only of More and William Penn, but of Jan Baptist van Helmont and Valentine Greatrakes, mystical thaumaturgists of the 17th century. Ragley became a centre of devotion and spiritualism. The rationality which distinguishes More's earlier works is much less conspicuous in his later works. He was a prolific writer of verse and in prose, but his works are now little known, except the Divine Dialogues (1688), a treatise which condenses his general view of philosophy and religion.
Henry More represents the mystical and theosophic side of the Cambridge movement. The Neoplatonic extravagances which lay hidden in the school from the first came to a head in his writings. He was a spiritual genius and a significant figure in British philosophy, less robust and in some respects less learned than Cudworth, but more fertile in thought. He describes himself as gifted with a buoyant temper. His own thoughts were to him a never-ending source of pleasurable excitement. He was known for his humility and charity as well as for his piety. The last ten years of his life were uneventful. He was buried in the chapel of the college he loved.
Before his death More issued complete editions of his works, his Opera theologica in 1675, and his Opera philosophica in 1678. The chief authorities for his life are Ward's Life (1710); the prefatio generalissima prefixed to his Opera omnia (1679); and also a general account of the manner and scope of his writings in an Apology published in 1664. The collection of his Philosophical Poems (1647), in which he has "compared his chief speculations and experiences," should also be consulted. An elaborate analysis of his life and works is given in John Tulloch's Rational Theology, vol. ii. (1874); see also R Zimmermann, Henry More und die vierte Dimension des Raums (Vienna, 1881).