In Paulo Choelho's The Alchemist, why did the alchemist leave Santiago alone at the end to complete his journey?

With regard to Paulo Choelho's novel, The
Alchemist, my first reaction is that at the end, Santiago must go on in order
to fulfill his Personal Legend—as as it is his—and he must do it
alone: it is his journey of
self-discovery.

Santiago has realized the connection he has
to God, and the powerful miracles he can perform because he is one with God. However, he
must travel to the Pyramids, which has been his goal all along, because of his
dreams.

However, when he arrives, he is attacked and beaten
by men who believe he has treasure. When they realize he has nothing, they prepare to
depart, but one of his attackers turns to him and he speaks of a
recurring dream he had had about going to Spain to find treasure in
a churchyard with a large tree...but what a foolish thing that
would be—to travel so far over a dream! What irony!

The boy
is elated: he had done such a foolish thing...traveling to the
Pyramids, and in doing so, the world opened up to him because he took the time to
listen, learn, and pay attention to omens, as God was speaking to
him.

The last pieces fall into
place:

The
boy stood up shakily, and looked once more at the Pyramids. They seemed to laugh at him,
and he laughed back, his heart bursting with joy.

Because
now he know where his treasure
was.

Had he not followed the
the path before him all along, he would not have realized that to fulfill his Personal
Legend, he has to return home to Spain where it all began.