Effectively in retirement, Vane wrote the "Retired Man's Meditations", published in 1655 amid rumours that Vane was fomenting rebellion against Cromwell, principally among Quakers and Fifth Monarchists. This work, a jargon-laden religious treatise in which Vane wanders between literal and symbolic interpretation of Biblical scriptures, was treated by contemporaries and later analysts, including David Hume, as "absolutely unintelligible" and "cloudily formed". The same year, after Cromwell called for a fast day to consider methods by which his government might be improved, Vane wrote "A Healing Question". In this more carefully structured political work, he proposed a new form of government based on a constitution decided by men attending a constitutional convention. He was encouraged to publish it by Charles Fleetwood, who had shown it to Cromwell. In a postscript to the work Vane wrote the words "the good old cause", a coinage that became a rallying cry in the next few years for Vane's group of republicans.