Meditation can mean either clearing your mind of all thought, or focusing on one thought, both done in an effort to achieve
enlightenment. For example, in some masters of "zen" or "chan" buddhism will give thier students koans to meditate on, such as, "What is the sound of
one hand clapping?". On the other hand, many other sects teach thinking of nothing. Either way can be effective for those who engage in the activity not for religious enlightment, but simply to relax and gain a greater
understanding of life.
He medidated on the koan and
understood that the lack of an answer was in itself an answer, and yet not the fullness of the answer.
I engage in meditation for
a few minutes before I
go to bed to help settle my mind.