opponents on their own chosen ground, and to subject their favorite speculations to a rigorous and sifting scrutiny; and this, not for the purpose of proving our fundamental position, for that must rest on its proper and independent evidence, but simply with the view of neutralizing the adverse presumptions which prevent many from considering its claims, and proving that it is a subject that demands and deserves their serious and sustained attention. Taking a comprehensive view of European Science and Literature during the last half century, we may discern the great currents, or chief tendencies, of speculative thought, in so far as it bears on the evidences and doctrines of Religion, in several distinct but closely related systems of opinion, which, whether considered severally or collectively, must exert, in proportion to their prevalence, a powerful influence on the side of Atheism. These systems may be divided generally into _two_ great classes, according as they relate to the _substance_ or to the _evidence_ of Theism, to the _truths_ which it involves, or the _proofs_ to which it appeals. The interval between the first and second French Revolutions may be regarded as the season during which the theories to which we refer were progressively developed, and ultimately consolidated in their existing forms. The germ of each of them may have existed before, and traces of them may be detected in the literature of the ancient world, and even in the writings of mediaeval times; nay, it might not be too much to affirm that in the systems of Oriental Superstition, and in the Schools of Grecian Skepticism, several of them were more fully taught in early times than they have yet been in Modern Europe, and that the recent attempts to reconstruct and reproduce them in a shape adapted to the present stage of civilization, have been poor and meagre in comparison with those more ancient efforts of unenlightened reason. What modern system of Skepticism can rival that of Sextus Empiricus? What code of Pantheism, French or German, can be said to equal the mystic dreams of the Vedanta School? What godless theory of Natural Law can compete with the Epicurean philosophy, as illustrated in the poetry of Lucretius? The errors of these ancient systems have been revived even amidst the light of the nineteenth century, and prevail to an extent that may seem to justify the apprehension, frequently expressed on the Continent of late years, of the restoration of a sort of Semi-Paganism in Modern Europe; and it is still necessary, therefore, for the defence of a pure Theism, to reexamine those ancient forms of error which have reaeppeared on the scene after it might have been supposed that they had vanished for ever. For the very tenacity with which they cleave to the human mind, and their perpetual recurrence at intervals along the whole course of the world's history, show that there must be something in the wants, or at least in the weaknesses of our