What events in Coelho's The Alchemist affect Santiago and shape his view of life?

In
Coelho's , there are many things that affect Santiago (the boy) and shape
his view of life, as well as his choices.

When Santiago has sold his sheep,
and is preparing to travel to Egypt to see the pyramids, a young man befriends himwho ultimately
steals Santiagos money, forcing him to take stock of his life. For a time he is in a desperate
state.

He was feeling sorry for himself, and lamenting the
fact that his life could have changed so suddenly and so drastically. 

In such a state, he cannot move forward. Santiago cleverly
convinces the crystal merchant to hire him on as a clerk, soon turning the business around, much
to the merchant's delight. For a good deal of the time he works, the boy plans to make enough
money to buy more sheep and return home. However, as Santiago listens to the crystal merchant
who turned his back on his dreams and still regrets iteven in the face of
financial successSantiago revisits his decision to turn back. Eventually,
he moves on,...