This quote means that Santiago trying to achieve his personal legend and listening to his heart, because it will not only make him happy but his heart happy. One day he will return and tell the tale of him going through his journey and inspire many other people to try and achieve their own legends. The heart should always be the first thing that tells you what to do, because it knows how to make yourself happy and when it shouldn't be happy.
This quote is when Santiago is talking to King Melchizedek about what he should do and try to get help and he says that happiness when you do something but also to not forget to about the little things in life. The little things in life is what makes life better and forgetting about that will just make it worse.
This quote means that everyone in the world understands each other somehow. Santiago is learning about the world and what it has for him. His understanding of the world is greater than anything, because at one part in life everyone understands each other and might have gone through the same things, but they don't know about.
This quote means that seeing the world will make you understand it more and get closer to your dreams when you can just see it right there. Santiago needs to see that the desert is his home and he travels with eyes open to understand the Soul of the World and find his personal legend. His eyes tell him where he needs to go and just understand the desert and what it holds a lot more clearer, because before he met the alchemist he would just walk the desert not understanding anything.
This quote means that anything can happen when you are following your heart. Following your heart can mean anything to achieving your dreams and how you can get there and however happy you can be. Achieving your dreams can open up the world a lot more learning about things you never knew about and meeting new people. Santiago is achieving his dreams and he has already met so many people and has already done so many things to get there.
Every second we are following our dreams it is farther away from suffering. You're making your heart happier the more closer we are to achieving your dreams. Your heart will always be happy and will never be in pain when it wants what it wants. God will be watching over him and will always help him get there. Santiago and the Alchemist are discussing how Santiago should achieve his dreams and his personal legends. He is getting closer to the treasure in his dreams.