It has been seen already that the risk of death increases with age. If, therefore, a level premium is to be paid throughout the duration of a policy, say from age 25 to 65, then the premium in the early years is higher than is needed and this 'reserve' is used to meet the cost of the greater risk in later years when the premium is less than is required to cover such a risk.
This diagram illustrates its difference from the natural premium method.