"The second thing in meditation, is, a serious and solemn thinking upon God. The Hebrew word to meditate, signifies with intenseness to recollect and gather together the thoughts. Meditation is not a cursory work, to have a few transient thoughts of religion; like the dogs of Nilus that lap and then run away; but there must be in meditation a fixing the heart upon the object, a steeping the thoughts. Carnal professors have their thoughts roving up and down, and will not fix on God; like the bird that hops from one branch to another, and stays in no one place. David was a man fit to meditate, "O God, my heart is fixed," Psalm 108:1.
In meditation there must be a staying of the thoughts upon the object; a man who rides quickly through a town or village—he minds nothing. But an artist who is looking on a curious piece, views the whole portraiture of it, he observes the symmetry and proportion, he minds every shadow and color. A carnal, flitting professor, is like the traveler, his thoughts ride hastily—he minds nothing of God. A wise Christian is like the artist, he views with seriousness, and ponders the things of religion, Luke 2:19. "But Mary kept all these things, and pondered them in her heart." (Thomas Watson)
(Thomas Watson's A Christian on the Mountaint, link)