Heaven and hell;
Our subconscious.
Meditation opens seldom glimpsed areas of our subconscious. When that happens, extraordinary thoughts and awareness come to us with seeming spontaneity. We realize truths that were opaque to us before; we perceive events that were previously too distant. But no one ever became superhuman because of meditation. They only opened their own latent potential. Everything is locked inside of us and need only be opened. That is why it is said that heaven is within us.
In the same way, the pains and the struggles of the past sometimes haunt us with astounding vehemence. Problems and conflicts are difficult to exorcise. Although we may practice spirituality and move on to new endeavors and relationships, past hurts still come back in our memories and dreams. These are not demons from another world, nor are they karmic manifestations of previous lives; they are scars in our subconscious. No matter how diligently we try to make progress, there still are pains that curse us day after day. This is why it is said that hell is within us.
We ourselves are the battleground for good and evil. There is no need to look beyond our world. Everything to be understood is within us. All that must be transcended — the pains and scars of the past — is within us. All the power of transcendence is also within us. Tap into it and you tap into the divine itself.