When one is totally occupied in any agreeable work that admits not many objects, time runs on without observation; and upon an after recollection must appear short, in proportion to the paucity of objects. This is still more remarkable in close contemplation and in deep thinking, where the train, composed wholly of ideas, proceeds with an extreme slow pace. Not only are the ideas few in number, but are apt to escape an after-reckoning. The like false reckoning of time may proceed from an opposite state of mind. In a reverie, where ideas float at random without making any impression, time goes on unheeded and the reckoning is lost. A reverie may be so profound as to prevent the recollection of any one idea: that the mind was busied in a train of thinking, will in general be remembered; but what was the subject, has quite escaped the memory. In such a case, we are altogether at a loss about the time: we have no _data_ for making a computation. No cause produceth so false a reckoning of time, as immoderate grief. The mind, in this state, is violently attached to a single object, and admits not a different thought. Any other object breaking in, is instantly banished, so as scarce to give an appearance of succession. In a reverie, we are uncertain of the time that is past: but in the example now given, there is an appearance of certainty, so far as the natural measure of time can be trusted, that the time must have been short, when the perceptions are so few in number. The natural measure of space appears more obscure than that of time. I venture however to enter upon it, leaving it to be further prosecuted, if it be thought of any importance. The space marked out for a house, appears considerably larger after it is divided into its proper parts. A piece of ground appears larger after it is surrounded with a fence; and still larger when it is made a garden and divided into different copartments. On the contrary, a large plain looks less after it is divided into parts. The sea must be excepted, which looks less from that very circumstance of not being divided into parts. A room of a moderate size appears larger when properly furnished. But when a very large room is furnished, I doubt whether it be not lessened in appearance. A room of a moderate size, looks less by having a ceiling lower than in proportion. The same low ceiling makes a very large room look larger than it is in reality. These experiments are by far too small a stock for a general theory. But they are all that occur at present; and without attempting any regular system, I shall satisfy myself with a few conjectures.