Perhaps you have never travelled in a hot-air balloon, but you know that what enables it to rise in the sky is the heat produced by the combustion of a gas, which inflates the canvas and makes the balloon lighter than air. The same is true in the spiritual life: to rise higher we must become light and dilated and, in order to become dilated, we must heat something within us. It is the warmth of love that inflates the heart and renders it so light that it begins to rise like a balloon.
You see, in order to move closer to heaven, it is more useful to know how to read the book of nature than the books of the theologians. The book of nature teaches you that when you become cold, you contract and become heavy, heavier than air, and you fall. And when you find yourself on the ground, you of course complain that heaven has abandoned you. But warm your heart, fill it with love, and you will rise once again and travel in space.
Omraam Mikhael Aivanhov