1. Isaiah Chapter 55 The Book of
The work of the suffering Servant in chapter 53 makes possible the offer of salvation in this chapter. In chapter 54 the invitation was confined to Israel. In this chapter the invitation is extended to the entire world.
The gospel went first to Israel and then to the Gentiles. I think this is what Paul meant when he said, "For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek" (Rom. 1:16). This does not mean that the Jew has top priority today, but he shouldn't have bottom priority either; he is on the same par as everyone else.

2. Isaiah – Chapter 55:1
1Ho, every one that thirsteth, come ye to the waters, and he that hath no money; come ye, buy, and eat; yea, come, buy wine and milk without money and without price.
"Ho" is like a startled cry for help in the night. He wants every weak soul to behold His mighty bared arm of salvation.
Spiritual thirst is primarily in view (see Ps 42:1–2; 63:1; Isa 41:17; 44:3). In hard times even water had to be purchased (see La 5:4), but here the water (a symbol of spiritual refreshment) — as well as the “wine” and “milk” (symbols of abundance, enjoyment and nourishment) — were free:
The invitation is ecumenical. I don't believe in the ecumenical movement that men talk about today, but I do believe in God's ecumenical movement, which is that the invitation of the gospel is to go out to the world. Everyone who thirsts, come to the waters: It is an invitation to everyone - but everyone who thirsts. Only those who thirst will come to the waters. If we aren't thirsty for what the LORD can give us, then we will never come to His waters.

3. Isaiah – Chapter 55:2
2Wherefore do ye spend money for that which is not bread? and your labour for that which satisfieth not? hearken diligently unto me, and eat ye that which is good, and let your soul delight itself in fatness. 
Food costs money, lasts only a short time, and meets only physical needs. But God offers us free nourishment that feeds our soul. How do we get it? We are to come (55:1), listen (55:2), seek, and call on God (55:6). God's salvation is freely offered, but to nourish our souls we must eagerly receive it. We will starve spiritually without this food as surely as we will starve physically without our daily bread.
It is ridiculous to spend one's hard-earned money for what does not satisfy, yet that is what multitudes of people do when they pursue things of only temporal value. The Lord urged the hearers to listen carefully to Him. They should choose what was satisfying and what would yield true abundance (cf. Matt. 6:19-21).

4. Isaiah – Chapter 55:3-4
3Incline your ear, and come unto me: hear, and your soul shall live; and I will make an everlasting covenant with you, even the sure mercies of David.  4Behold, I have given him for a witness to the people, a leader and commander to the people.
The reference to the “sure mercies of David” speaks of the Davidic covenant (2 Sam. 7), which promises that a descendant of David will rule eternally over a kingdom that will bless all the nations (cf. Luke 1:32, 33; 2:30-32).
Quoted by the Apostle Paul in Acts 13:34 in his sermon at Antioch in Pisidia and applied to the resurrection of Jesus from the dead.
An everlasting covenant. This term appears in 61:8; Jer. 32:40; Ezek. 37:26, referring to the experience of the returned exiles. steadfast, sure love for David. The blessing is focused on the house of David, out of which the messianic servant will arise (cited from the Septuagint in Acts 13:34).

5. Isaiah – Chapter 55:5
5Behold, thou shalt call a nation that thou knowest not, and nations that knew not thee shall run unto thee because of the LORD thy God, and for the Holy One of Israel; for he hath glorified thee.
Although God's message has been to the Jews, He has opened that invitation up to everyone. But now, we see that He is specifically addressing the nation of Israel, when He lets them know that there is another nation that will come running to them because of the Lord glorifying them.
Israel's royal status yields benefits for all humanity, who come to recognize, as a result of her redemption, the one true God.

6. Isaiah – Chapter 55:6-7
6Seek ye the LORD while he may be found, call ye upon him while he is near: 7Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and he will have mercy upon him; and to our God, for he will abundantly pardon.
Seek the LORD while He may be found: The prophet impresses a sense of urgency on God's people. "This is the time. God can be found now. Seek Him now." It isn't that God is hidden, and can only be found now. It is that He can only be found when our hearts are inclined to look for Him, and that inclination itself is a gift from God!
Let the wicked forsake his way: The prophet impresses the need for repentance among God's people. Repentance is simply turning around our way - turning from our own way, turning unto God's way.

7. Isaiah – Chapter 55:8-9
8For my thoughts are not your thoughts, neither are your ways my ways, saith the LORD.  9For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts. 
God's compassion on those who turn to Him (vv. 6-7) comes because His thoughts and ways are far superior to human thoughts and ways, which in fact are evil (cf. v. 7). God's plan is something people would have never dreamed of.
Sinners need to forsake their ways and thoughts (actions and attitudes, v. 7) because they are not God's ways and thoughts. God's way is forgiveness and His thoughts are compassionate (v. 7), as far different from those of sinners as the heavens are higher than the earth. Sinners must make a break with their thoughts and ways to have fellowship with a holy God. The Servant's work makes relationship with a holy God possible, but our work, having appropriated the Servant's work by faith, makes intimate fellowship with a holy God possible.

8. Isaiah – Chapter 55:10
10For as the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and maketh it bring forth and bud, that it may give seed to the sower, and bread to the eater:
In this closing section there is a prominence given to the Word of God. The only place where the gospel is found is in the Word of God. Salvation is a revelation of God, and the Word of God is likened to the rain that comes down from heaven. You see, the gospel is not asking you to do something. Neither is the gospel something that man has thought up. Man does not work his way up to God by some Tower of Babel effort, but he receives God's revelation which comes down from heaven like rain. The rain causes the earth to become fruitful. The seeds germinate and fructify and bring forth abundantly. The Word of God is also the seed; and, when the rain and seed get together in the human heart, there will be fruit.

9. Isaiah – Chapter 55:11
11So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it. 
It shall accomplish what I please: God's Word has something to accomplish. God doesn't just speak to hear Himself talk. His Word is not empty, or lacking in power. This also means that God's Word has a purpose. He didn't speak in unfathomable mysteries just to blow our minds, or confuse us, or leave things up to any possible interpretation. When God speaks, He speaks to accomplish a purpose.
It shall prosper in the thing for which I sent it: God's Word doesn't "barely" get the job done. It shall prosper in the purpose God has for it. It is rich and full of life. God's Word always succeeds, and always fulfills God's purpose.

10. Isaiah – Chapter 55:12
12For ye shall go out with joy, and be led forth with peace: the mountains and the hills shall break forth before you into singing, and all the trees of the field shall clap their hands. 
Go out (or forth) from the lands of your wanderings, referring again to the final and complete regathering of Israel from all nations (Isa. 11:10-12, notes). In their regathering at the second coming of Christ, the mountains, hills, and trees of Palestine are to rejoice at their return. In that day the curse will be removed from plants and trees, and the state of all things will be as before the fall of Adam (Isa. 55:13; 35:1-10; cp. Ps. 98:8).

11. Isaiah – Chapter 55:13
13Instead of the thorn shall come up the fir tree, and instead of the brier shall come up the myrtle tree: and it shall be to the LORD for a name, for an everlasting sign that shall not be cut off.
This verse looks forward to the Millennium when the earth will be redeemed from the curse of sin. The curse of sin is expressed by the thorn and brier. When Christ died, He not only redeemed sinners, He also redeemed a sin-cursed earth.
The replanting of productive, desirable trees and shrubs (representing all creation), in place of plants bearing the marks of the Fall and its curse, symbolizes the rejuvenation of creation. This transformation, and behind it the redemption accomplished by the Servant, would be a memorial that would honor Yahweh. It would be an everlasting sign of God's salvation that would remain forever.

12. Isaiah – Chapter 55
End of Chapter 55
The prophet concludes both this chapter and all of chs with a vision of the triumph of God's grace, when the effects of sin and the fall (see Gen. 3:17; 6:11–13) are rectified and “the creation itself will be set free from its bondage to corruption and obtain the freedom of the glory of the children of God” (Rom. 8:21). before you.