In the philosophy of external matter, the greater or less familiarity of events produces an illusion exactly similar. There are certain phenomena, which, we readily admit, could not, of themselves, and without experience, have indicated to us, either the changes which preceded them, or the changes which were to follow; while there are other phenomena, more familiar, which seem to us to require no experience, for informing us, both of their antecedents and consequents,--merely because they have been of such frequent occurrence, that we do not remember the time, when we were ignorant of them, or of the circumstances, by which they are usually preceded and followed. That a magnetic needle should tend to the north, rather than to any other point,--and that glass, or amber, rubbed in a certain manner, should exhibit the very striking phenomena of electricity, transmitting this power through certain substances, and not transmitting it through others, which have nothing peculiar in their sensible qualities, to mark them as less or better fitted for this communication, appear to us to be facts, which we could not have known, till we had actually witnessed them. But that a stone, rolled from the hand, should continue to move in the same direction, after quitting the hand, seems a fact, which it must have been easy for us to foresee. We are not aware, that it is only the more familiar occurrence of the one event, than of the others, which makes its sequence appear more obvious; and that, but for this greater familiarity, we might as readily have supposed, that a stone, after quitting the hand which flung it, should have remained in the air, or fallen to the ground, as that the needle, without any tendency to the north, would remain stationary, to whatever point of the compass we might turn it. Such is the influence of early acquaintance with the more frequent and obvious events, whether in mind or in matter. We have become familiar with them, and with their causes and consequences, long before reflection; and it is not very wonderful, that we should conceive ourselves to have _known always_, what we do not remember to have ever learned.