1. The infant in w/c people pay attention to its needs,
2. The child/whining schoolboy 
3. the lover/youth
4. the soldier, it's actually a metaphor that may suggest that in this period of time we start taking our jobs seriously and start working hard.
5. The old man, in w/c many of the traits he used to posses slowly diminishes and his childish traits start to appear again.
6. Justice/judge,  the period of time that you gain importance and no longer trying to prove yourself.
7. Death is the final stage wherein you lose everything; sans everything.