When I use the term "Christian Ignorance," I would not have either the sense which I attach to the expression, or the intention with which I use it, misunderstood. I do not think that it should be denied to man to make any use of his intelligence, to exercise any right to inquire freely after truth, or after any kind of truth. Is the field which is open to the human mind limited in extent? Is the mind itself of limited reach? Is there a difference of degree in human knowledge according as the objects are different to which it is applied? These are questions, all of them, fundamentally contained in the words "Christian Ignorance;" and of these questions it is my aim to offer what appears to me to be the right solution. {129} I am in the presence of four sciences, and of six schools or systems, which have made, are making, and will always continue to make, much noise in the world. The sciences are, Physiology, Psychology, Ontology, and Theology. The systems to which these sciences have given birth are, Materialism, Positivism, Scepticism, Spiritualism, Scientific Theology, Mystical Theology. I am far from meaning to discuss here the principles of these systems, or to attempt to determine their value; it would be to undertake the task of examining all philosophy and all philosophies. I mean to touch only upon one of the special questions which furnish in our days matter of debate between Christianity and these different schools. It is thus, and thus only, that I can clearly establish the sense which I attach to the words "Christian Ignorance;" and determine, at the same time, their bearing and their limitation. {130} I have, and for very simple reasons, little to say respecting the first three systems to which I have just referred, i. e., Materialism, Positivism, Scepticism. By its denial of the distinction of the soul and the body, of mind and matter, Materialism rejects Psychology, and arrives, as far as Ontology is concerned, only at Atheism or at Pantheism. Of the four great philosophical sciences, Physiology is the only one with which Materialism has any concern. Amongst Positivists, some, the more eminent, admit, it is true, the reality of Objects, or to speak more exactly, the reality of the domain of Psychology and of Ontology; but in admitting it they declare it to be inaccessible to the human mind: "Inaccessible," says M. Littré, "not null or non-existent; it is an ocean which washes our shore, and for which we have neither bark nor sail." [Footnote 36] [Footnote 36: A. Comte et la Philosophie Positive. By M. Littré, p. 519.]