Husband and wife will warm each other as they lie side by side in the same bed, and David in his old age needed the warmth of another human being to keep his aging and ailing body from losing all heat. But this is only an illustration in Solomon’s argument of the true warmth.
The soul without Christ runs out of inner resources to supply its own heat, the light of its own fire soon dies down (Isaiah 50:11). All its heat is drained by the vast expanse of purposelessness and meaningless around it, for a world without God is meaningless and if we reject him, we must create our own meaning out of nothing. The Christian has a Saviour who has promised never to leave him or forsake him and can be relied upon in the hour of need. Our Saviour will not leave us as orphans in this world but will come to us. He has sent another the Comforter to us to be with us forever. That promise of eternal companionship is the ultimate meaning of this lesson on not being alone.