‘If that sublime idea of the ancients that there is only one species of matter in the universe, and that its different properties depend on the difference of size, shape and other qualities should be confirmed, it would simplify the science in a most eminent degree, and at the same time it would raise it to the acme of perfection.’ Opposing the view that oxygen gas contained light combined with it, and gave light out in oxidation, he contrasted slowly oxidised iron with an iron turning burnt in oxygen. ‘When the laws which govern in chemical science are fully known, there is no doubt it will become a much more simple science. It cannot fail to be so, since then it will be complete. Already it is one of the most useful of the whole circle to man, and when in its utmost state of improvement it will be one of the most sublime. It will, I have no doubt, connect mechanical and chemical sciences together; it will concentrate them into one and in that one comprehend the whole universe. ‘The first step to truth is the confession of ignorance. No man could have made the immortal discoveries of Newton unless he had first thrown up the ridiculous doctrines of Des Cartes. To attend to our errors and own them, to sacrifice all selfishness to the science, not to support errors for the sake of vanity, ought to be the leading precepts of a philosopher. He should turn his endeavour to the advancement of science and not to the increase of his reputation. Let him fix steps for others to rise on, and he does more real good to science than if he had spent years in controversy on an equivocal point. Let him turn his thoughts to general views and try to contain the whole science in his grasp; he will then be calculated to arrange it, improve it, and reform it and place it in that order which tends so materially to its advancement.’ His lecture on Chlorine was given on Saturday, March 14; the previous week he had given a lecture on Oxygen, which was not reported by Faraday. ‘I will demonstrate what I affirm in a positive and satisfactory manner. ‘Accustomed for years to consider the chemical principles of the French School of Physical Sciences as correct, I had adopted them and put faith in them until they became prejudices, and I even felt unwilling to give them up when my judgment was fully convinced by experiment that they were erroneous. I know that this is the case in some degree with almost every person; he is unwilling to believe that he is wrong, and therefore feels averse to adopt what is right when it opposes his principles.