Time preference is closely related to the important concepts of saving and investment. Saving is the withholding of a good from consumption or from allocation to another end that would have led to earlier consumption. Investment is the allocation of a good to production instead of immediate consumption, or to a longer production process rather than a shorter one. Instead of taking the time to fashion the axe, Crusoe could have proceeded to use the cutting rock as originally planned, thus obtaining his first tree house more rapidly. He decides instead to defer consumption. Saving his labor and other factors from uses that would have brought him more immediate gratification, he instead invests them into a process with a longer period of production. Clearly, saving and investment go hand in hand. A good is saved only in order to invest it; conversely, a good cannot be invested unless it has been saved from some other potential use. The necessary relationship between saving and investment is often overlooked by the economically misinformed. In a larger economy, investment (and consequent productivity increases) cannot be attained without improvements in the savings rate.