Pre-existence (17a): Three statements further describe the exalted Christ. First, He is before all created things. Even though His incarnation took place after creation, His existence as God predates creation. Scripture resounds with this pre-existence of the Son. He was with the Father in divine glory "before the world was" (John 17:5). He lived in intimate fellowship with the Father before creation (John 1:1-3). All things came into being through Him (1:16; John 1:3; Heb. 1:2). Scripture repeatedly affirms: Christ is before all things.
Formation (17b): Paul adds another dimension to Christ's creatorhood: "in Him all things have held together." Unlike the verb "create," "hold together" highlights the actual formation of matter in creation. This is to say, all matter came together in Christ. Whether stars, planets, continents, rocks, molecules or atoms, everything in this tangible universe owes its physical form to Christ!
Headship (18a): The Son's supremacy over the cosmos ("all things") is now applied to His people, the church. The Creator of the universe does not curtail His authority when it comes to His own spiritual body (1:24). And just as the head controls the body and the body naturally carries out the will of its head, so also Christ directs us with His Word, and we carry it out. Christ is our head!
 1:15 is actually a relative clause: "who is." This is followed by three statements joined by "and [kai (καί)]" (1:17-18a). 1:18b repeats largely the same structure, with words like: firstborn, all things, heavens and earth.
 "All things" point to the all created things previously mentioned in 1:16.
 This verb is in the perfect tense which NASB renders as present.
 The verb sun-i-stē-mi (συνίστημι) points this out. The verb's meaning is to cohere or to form (2 Pet. 3:5).
 Christ's authority was seen earlier in 1:15 ("all things have been created for Him"). "Head" is a common metaphor for authority (1 Cor. 11:3; Eph. 1:22; 5:23), and it's used this way also in Col. 2:10.
 Christ's physical body (1:22) is distinct from the spiritual church body (2:19; 3:15; Eph. 2:22; 1 Cor. 3:16).