What is santiago's objective, what does he want and what is his motivation, the reason for wanting it?

Santiago has a dream, a calling. The child showing him a treasure at the base of the Pyramids floods his brain in his restless sleep. Santiago needs to know what it means. THe gypsy of Tarifa and Melchizedek both implore Santiago to follow it, because, they argue, dreams are the language in which the Universe speaks. THere is a longing in every human soul which transcends the here and now. Santiago has a calling that just might explain why he was put on this earth. There is no greater motivation than that.