This verse imparts to us a technique of meditation. Recall that in Biblical Hebrew the word for heart also means mind. Thus, quiet yourself, and still your mind. When your mind begins to wander or think about other things, calmly return it to a state of quietness. It will frequently run after other things, but just keep returning it to the stillness within. Constantly engage in this "running and returning", and in this manner, a covenant, an agreement, a path will be established between the world of form and that which is beyond form.
"The Lord passed by, and a great and strong wind tore the mountains, and broke in pieces the rocks before the Lord; but the Lord was not in the wind; and after the wind an earthquake; but the Lord was not in the earthquake; And after the earthquake a fire; but the Lord was not in the fire; and after the fire a still small voice. -Kings I 19:11-12"
"And I looked, and, behold, a stormy wind came from the north, a great cloud, and a fire flaring up, and a brightness was around it, out of its midst, Chashmal*, out of the midst of the fire. -Ezekiel 1:4"
*The word "Chasmal" is often translated as "color of amber" or "electricum" in many Bibles. However, according to the Talmud (Chagigah 13a), this word is actually a concatenation of words for "silence" and for "speech". Thus, reread the above passage this time substituting the phrase "speaking silence" or "silent speech" for Chasmal.