Meditations 9:32

You can discard most of the junk that clutters your mind—things that exist only there—and clear out space for yourself:

. . . by comprehending the scale of the world

. . . by contemplating infinite time

. . . by thinking of the speed with which things change—each part of every thing; the narrow space between our birth and death; the infinite time before; the equally unbounded time that follows.