That is to say, that, according to Positivists, Psychology, Ontology, and Theology are not--cannot be--sciences. {131} As for sceptics, they contest to the human mind all certitude, and especially certitude with respect to the subject-matters of Psychology, Ontology, and Theology. The fundamental principle of Christian belief is then too absolutely strange to those three schools for it to be necessary that I should discuss with them the source, bearing, and legitimacy of that which I term "Christian Ignorance." It is only with Spiritualists, with scientific Theologians, and with mystic Theologians, that it is possible to discuss this question of Christian Ignorance, for the three schools to which they belong are the only ones which, in the same way as Christianity itself does, open to the human mind the domain of the four sciences--Physiology, Psychology, Ontology, and Theology, and which recognise the right of the human mind there to search after truth, and the possibility of its being there discovered. When I speak of Spiritualists, a preliminary remark is indispensable. Christianity is as spiritualistic, not to say more so, than Spiritualism itself. {132} It is not, then, with Spiritualism in general, and with all Spiritualists without distinction, that Christians have to deal in the question of "Christian Ignorance," as it has in other questions; the discussion here lies between Christianity and Rationalistic Spiritualism alone; and not only between Rationalism and Christian ignorance, but also between Rationalistic science and Christian science.