I read a book long time ago in which the author wrote the sentence, 'There is no world outside'. I don't remember the title nor the author's name of the book. But the sentence has been stuck with me since then up until now. 

Then finally, I feel I have deciphered the meaning of the sentence.

Mind is not a thing but activities. And you are not your mind just same as you are not your body. So, what are you? This is a tough question to be answered.

"Mind is the Master power that moulds and makes." - James Allen

Once we get the truth that the ultimate cause of our results is always ourselves specifically our mind, things get much simpler. Here is how it works. Your mind is the cause of your actions. And your actions are the cause of your results. So, it is better to know more about what mind is.

To get preferable results for our life, we first need to know the law of  laws, which is 'cause & effect'. It simply says there is cause before effect. In other words, things don't just happen. If we understand the relation between a certain cause and effect, we can take advantage of it. We can create preferable results in our lives not by chance but by design. It sounds really great, doesn't it?