measure, the regularity of their operation. I am here seated in my chamber with my face to the fire; and all the objects, that strike my senses, are contain'd in a few yards around me. My memory, indeed, informs me of the existence of many objects; but then this information extends not beyond their past existence, nor do either my senses or memory give any testimony to the continuance of their being. When therefore I am thus seated, and revolve over these thoughts, I hear on a sudden a noise as of a door turning upon its hinges; and a little after see a porter, who advances towards me. This gives occasion to many new reflections and reasonings. First, I never have observ'd, that this noise cou'd proceed from any thing but the motion of a door; and therefore conclude, that the present phænomenon is a contradiction to all past experience, unless the door, which I remember on t'other side the chamber, be still in being. Again, I have always found, that a human body was possest of a quality, which I call gravity, and which hinders it from mounting in the air, as this porter must have done to arrive at my chamber, unless the stairs I remember be not annihilated by my absence. But this is not all. I receive a letter, which upon opening it I perceive by the hand-writing and subscription to have come from a friend, who says he is two hundred leagues distant. 'Tis evident I can never account for this phænomenon, conformable to my experience in other instances, without spreading out in my mind the whole sea and continent between us, and supposing the effects and continu'd existence of posts and ferries, according to my memory and observation. To consider these phænomena of the porter and letter in a certain light, they are contradictions to common experience, and may be regarded as objections to those maxims, which we form concerning the connexions of causes and effects. I am accustom'd to hear such a sound, and see such an object in motion at the same time. I have not receiv'd in this particular instance both these perceptions.
These observations are contrary, unless I suppose that the