An outstanding characteristic of it is its sudden changes of persons; "He," "I," and "thou" alternate in a bewildering fashion, which has led to many attempts at explanation. One point is clear--that, in vv. 14-16, God speaks, and that He speaks of, not to, the person who loves and clings to Him. At ver. 14, then, we must suppose a change of speaker, which is unmarked by any introductory formula. Looking back over the remainder of the psalm, we find that the bulk of it is addressed directly _to_ a person who must be the same as is spoken _of_ in the Divine promises. The "him" of the latter is the "thee" of the mass of the psalm. But this mass is broken at two points by clauses alike in meaning, and containing expressions of trust (vv. 2, 9_a_). Obviously the unity of the psalm requires that the "I" of these two verses should be the "thou" of the great portion of the psalm, and the "he" of the last part. Each profession of trust will then be followed by assurances of safety thence resulting, ver. 2 having for pendant vv. 3-8, and ver. 9_a_ being followed by vv. 9_b_-13. The two utterances of personal faith are substantially identical, and the assurances which succeed them are also in effect the same. It is by some supposed that this alternation of persons is due simply to the poet expressing partly "his own feelings as from himself, and partly as if they were uttered by another" (Perowne after Ewald). But that is not an explanation of the structure; it is only a statement of the structure which requires to be explained. No doubt the poet is expressing his own feelings or convictions all through the psalm: but why does he express them in this singular fashion? The explanation which is given by Delitzsch, Stier, Cheyne and many others takes the psalm to be antiphonal, and distributes the parts among the voices of a choir, with some variations in the allocation. But ver. 1 still remains a difficulty. As it stands it sounds flat and tautological, and hence attempts have been made to amend it, which will presently be referred to. But it will fall into the general antiphonal scheme, if it is regarded as a prelude, sung by the same voice which twice answers the single singer with choral assurances that reward his trust. We, then, have this distribution of parts: ver. 1, the broad statement of the blessedness of dwelling with God; ver. 2, a solo, the voice of a heart encouraged thereby to exercise personal trust; vv. 3-8, answers, setting forth the security of such a refuge; ver. 9_a_, solo, reiterating with sweet monotony the word of trust; vv. 9_b_-13, the first voice or chorus repeating with some variation the assurances of vv. 3-8; and vv. 14-16, God's acceptance of the trust and confirmation of the assurances.