The subsequent history of Hume's theory of Cause and Effect, is a marked illustration of the danger of bringing forward as an argument against theories purely metaphysical, the statement that they are dangerous to religion. It is difficult to see where there is a difference between adducing that argument in the sphere of natural philosophy, from which it has been long scouted by common consent, and bringing it forward as an answer to the theories of the metaphysician. In either case it is a threat, which, in the days of Galileo, bore the terror of corporal punishment, and in the present day carries the threat of unpopularity, to the person against whom it is used.[86:1] If any one should suppose that he finds lurking in the speculations of some metaphysical writer, opinions from which it may be inferred that he is not possessed of the hopes and consolations of the Christian, humanity to the unhappy author should suggest that he ought rather to be pitied than condemned, and respect for the religious feelings of others should teach that there is no occasion to endeavour, by a laborious pleading, to demonstrate that a man who has said nothing against religion is in reality an enemy to Christianity. They are surely no enlightened friends to religion, who maintain that the suppression of inquiry as to the material or the immaterial world, is favourable to the cause of revealed truth. The blasphemer who raises his voice offensively and contentiously against what his fellow citizens hold sacred, invokes the public wrath, and is no just object of sympathy. The extent of his punishment is regretted only when, by its vindictive excess, it is liable to excite retaliatory attacks from the same quarter. But the speculative philosopher, who does not directly interfere with the religion of his neighbours, should be left to the peaceful pursuit of his inquiries; and those who, instead of meeting him by fair argument, cry out irreligion, and call in the mob to their aid, should reflect first, whether it is absolutely certain that they are right in their conclusion, that his inquiries, if carried out, would be inimical to religion--whether some mind more acute and philosophical than their own, may not either finally confute the sceptical philosopher's argument, or prove that it is not inimical to religion; and secondly, whether they are not likely to be themselves the greatest foes to religion, by holding that it requires such defence, and the practical blasphemers, by proclaiming that religion is in danger?