 The paths of capital and labor will be determined by the aggregation of the saving and labor supply decisions of the individual agents alive through time.Thus a young person's decision about consuming and working today depends, in part, on what he believes will be the interest and wage rates when he's middle age and old, for example, age 90.But the value of these factor prices when he's age 90 depend on how much capital and labor will be around in that year.