what we do on a daily basis is possible because of what someone else did in the past. In this case there would be no shade had there not been a tree planted at some point. Same goes for most things, this saying is simply trying to bring attention to the fact that in a way everything is linked and everything that is done has lasting results and in order to make your lasting results beneficial to future generations you should always consider the repercussions of what you do and how your actions will impact others

SOURCE:http://blog.iyodatv.com/todays-motivational-quote/