O human being who is in love with the fleeting world, in forgetfulness of the Eternal One! Know that your world is actually a narrow grave, even though you imagine it to be spacious. The walls of your small space are made up of glass, and you get deluded with the mirror effect: the glass walls reflect on each other and you think your small space is as big as a city. That is, your past and your future reflect within each other and your present moment seems spacious to you. In reality, you only have a fleeting present at hand, and both past and future are nonexistent. You confuse reality with imagination, and assume that a nonexistent world is present with you.
Indeed, this illusion is similar to seeing a two dimensional thing, such as a line, as three dimensional, like a surface, because of its fast movement. The reality of your existence is as thin as a line and your world is so narrow. And yet, because of your illusion, forgetfulness, and imagination your world seems vast to you, and the walls of your place seem to be far out there. In reality, if you were to wiggle a bit within your narrow place -which happens when a calamity hits you in life-, then you will immediately hit the wall that seemed so far away. That is, the calamities wake you up and do away with your illusion. Then, you see that your vast world is in fact as tight as a tomb, and narrow like a slim bridge. Your lifespan passes in lightening speed, and your life flows faster than a river.
Now, if the life of this world, and the physical and animal life is such, then you come out of the animal level. Give up being stuck in corporeality, enter into the higher level of the heart and the spirit. You shall find a life much more spacious than the vast world you used to imagine. You will find a realm of light. The key to that world is in tawhid: in “there is no god except God.” This phrase contains the secrets of knowledge of God (ma’rifatullah) and oneness of God (waḥdaniyya). Let your heart speak with it and let your spirit flourish with it.