And He laid His right hand upon me, saying unto me, Fear not; I am the first and the last: I am He that liveth, and was dead; and behold, I am alive for evermore, Amen. – Revelation 1:17,18

As to the Lord’s person, Jesus revealed to His disciple that He was most truly divine. “I am the first and the last.” This language can be used of none but God Himself; none but He is first; none but He is last; none but God can be first and last. Now, our Lord Jesus Christ was evidently first. He existed before He was born into the world. We read, “a body hast Thou prepared Me.” Then Christ was a previously existing one for whom that body was prepared; and He it is who said, “Lo, I come, to do Thy will O God.” He came into the world, but He had from old eternity dwelt in the bosom of the Father. John the Baptist was born into the world before the Savior, of whom he was the forerunner, but what does he say? His testimony is “He, coming after me, is preferred before me, for He was before me.” He is first in order of honor because first in order of existence. John was the elder as man, but as God the Lord Jesus is from everlasting. Go back in history as far as you will; with one leap ascend to the days of Moses, and there is Christ before you, for we read: “Let us not tempt Christ as some of them also tempted and were destroyed of serpents.” There was Christ, then, in the wilderness vexed by the people. He it was whose voice then shook the earth, but who will yet shake not the earth only but also heaven.

By the words “the first and the last” are signified, in most languages, the sum and substance of all things. We say sometimes the top and the bottom of it is so and so; we mean that it is the whole of it. And the Greeks were wont to say, “This is the prow and stern of the business,” meaning that it is the whole. And so Jesus Christ, in being first and last, is all in all. And, truly, it is so in the working of redemption and salvation; He begins, carries on, completes; He asks no creature help and will have none. To us He is the author and the finisher of our faith, the alpha of our first comfort, and the omega of our final bliss. ~ C.H. Spurgeon

 https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1028.cfm