Why is the past the necessary condition for the present?

1 = {1}, 2 = {1,2}, …

one = {first}, two = {first, second}, …   

e.g. a necessary condition of having 3 apples is having 2 apples.

— Me@2011.07.05

— Me@2011.07.29

2011.07.29 Friday (c) All rights reserved by ACHK