Throughout the latter half of the sixteenth century John Dee enjoyed a thoroughly European reputation for profound scholarship: his opinions were widely consulted, his authority invoked in many diverse fields of speculation and research. Yet, without minimising the value of his personal influence and attainments, the justification for a detailed study of these must depend less on the limited value of the accompanying attempt to assess Dee's own claims as an original thinker or direct contributor to scientific discovery, than on the fact that he may be significantly considered as the representative - and in some respects the spokesman - of an age. Dee in his life and writings championed a certain vigorous "new philosophy" which flourished in the late Renaissance(1), and though this philosophy, or rather the particular form which it then assumed, fell later into barren obsolescence (2) yet some of its offshoots of that time were to bear rich, and unexpected fruit in succeeding centuries. Dee's surviving works are perhaps only fragmentary illustrations of certain aspects of the general body of doctrine he maintained, yet an examination of them is illuminating since, however limited or idiosyncratic their subject matter, they exemplify a typical approach to various problems, and they also occasionally give clear expression to broad statements of principle, which should, Dee believed, provide a foundation for a multitude of particular applications. In these respects, they throw some light, if only indirectly, on much contemporary endeavour and achievement, even in fields discussed not at all, or only incidentally, by Dee, since these may often properly be regarded as related and comparable effects arising from a common intellectual tradition.

The movement to which Dee contributed may be described rather broadly as striving after a new philosophic synthesis which should fully express and relate, as far as they could be known from the data of reason, revelation, and experience, both the capacities of men and the processes of nature, and which should relegate neither to a subordinate or derivative position in regard to the other. It has a natural place, frequently acknowledged by its exponents, in the general stream of neoplatonism, but it is more particularly associated with that current, which embracing much of later Greek endeavour in astronomy and mathematics, stemmed from Alexandria, notably preserving thereafter, from this source, the characteristic emphasis on the natural powers of the Intellect to arrive at truth, and on the value of dialectic, with the corresponding lack of stress on the immediate importance of "ecstasy" (reflected in the Greek patristic writers' comparative neglect of the doctrines of Original Sin and Grace), and ran through much of the scientific thought of the Arabs; which current, by insisting that the Cosmos was a logical and necessary unfolding of intelligible principles, emanating from and manifesting the nature of God, gave strong support and encouragement to the study of the natural sciences and mathematics. That other aspect of neoplatonism - the only one of much influence in the Latin speaking world during the middle ages, represented by the writings of the Pseudo-Dionysius, and to some extent those of St. Augustine, which stressed, or was inclined to value above all else, the personal mystic experience - to which all knowledge and philosophy was considered at best, merely a propaedeutic, since true knowledge was essentially revealed and not attained to - this aspect was of course incorporated into the scientific neoplatonism of the Renaissance - to have excluded it would have introduced incoherency and inconsistency into a doctrine relying so much on the assertion of the mind's ability, owing to its relationship with the creative thought of God, to determine a priori, at least criteria of, truth. Nevertheless it was overshadowed in the sixteenth century by the rediscovery of, or by the increased attention then given to, the works of later Greek Platonists - the mathematical and metaphysical commentaries of Proclus for example, whose writings make up one of the chief single influences on Dee's thought in general - as well as ancient scientific writings either associated with these, or at least having little relation with and frequently running counter to Aristotelian doctrines - and the theological writings of the Greek Fathers, who presented a much more explicit synthesis of Christianity and pagan philosophy, the essential harmony between which was affirmed by Justus, Clement, Gregory and others, than any of the Latin Fathers had been prepared to do. The form this Neoplatonism assumed and the applications of its doctrines, in the late Renaissance, of which Dee's work is here considered to be representative, and which were to give a new character to the scientific, or philosophical, approach to Nature in his time, bore fruits in fields far removed from Dee's own immediate interests; for while his own practical achievements, in kind and in extent, remained somewhat narrowly limited, the principles from which they sprung, and the method by which they were developed, were widely proclaimed and accepted as possessing universal validity throughout the "natural," "intellectual," and "spiritual" worlds, and as providing guiding canons for practice of the various arts as well as invention or discovery in mechanics and natural sciences.