"Thou, Lord, in the beginning hast laid the foundation of the earth; and the heavens are the works of Thine hands: they shall perish; but Thou remainest; and they all shall wax old as doth a garment; and as a vesture shalt Thou fold them up, and they shall be changed: but Thou art the same, and Thy years shall not fail" (Hebrews 1:12-14).
The sands of the world continually shift under our feet, and regardless of how stable a foundation we attempt to establish, life brings to us uncertainty. "The world passeth away" (I John 2:17).
Against this backdrop, the written Word of God presents to us the living Word of God as the only truly stable reality in our lives. "Thou are the same" declares Scripture of the Lord Jesus Christ, and furthermore proclaims of the Savior, "other foundation can no man lay than that is laid, which is Jesus Christ" (I Corinthians 3:11). There is therefore solid ground in our lives, but we must determine to walk upon it if we are to experience the peace of heart promised by our Lord's eternal stability.
This journey upon an unchanging path requires the renouncing of trust in anything or anyone of whom it cannot be said, "Thou art the same." This includes everything and everybody. In principle, this sounds right and reasonable, and deep in the hearts of God's trusting children, we know it is true. However, the world, the devil, and the flesh (including our own flesh) war against the affirmation of the Lord Jesus as our only firm footing. There is no greater challenge in life than to genuinely heed the mandate of Solomon: "Trust in the Lord will all thine heart, and lean not unto thine own understanding" (Proverbs 3:5). Our "own understanding" processes claims of security from many imposters, and left to itself will seek to navigate the paths of life on the most obviously shaky foundations.
"The Lord is my rock... in whom I will trust" (Psalm 18:2). David's confession must be our confession. We must walk upon the same path of "Thou art the same" upon which our brother of old walked. There is no other safe footing. No other human being can be this for us. No place or circumstance or condition can be expected to forever remain the same. And no foundation laid by our own hands and devices offers to us "the way of holiness" paved by the perfect faithfulness of the Lord Jesus (Isaiah 35:8). Yes, let all other ground shift and move under our feet as "the world passeth away." If our hearts are grounded and founded upon the solid rock of "Thou art the same," and "the Lord is my rock," we shall be at peace. There is no other firm footing, and we need no other.
"Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock: and the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock. And every one that heareth these sayings of mine, and doeth them not, shall be likened unto a foolish man, which built his house upon the sand: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell: and great was the fall of it."