John Wesley's pneumatology

Perceptible inspiration', a term used by John Wesley to describe the complicated relationship between Holy Spirit, religious knowledge, and the nature of spiritual being, is not unlike the term 'Methodist' which was also coined by critics of Methodism during the eighteenth century in Britain. Wesley's adversaries - especially the pseudonymous "John Smith," with whom Wesley exchanged letters for a period of three years - frequently attacked the plausibility of such a thing as direct spiritual sensation, which Wesley in turn defended. What exactly did he mean by perceptible inspiration?