In William Blake's Songs of Innocence and Experience, the poet connects the lamb, the child, and Christ through symbolism. Let's look at some examples of this.

In “Introduction,” the speaker meets a mysterious child who is sitting on a cloud. The child laughs and tells the speaker, “Pipe a song about a Lamb!” The child then weeps at the song. The symbolism is heavy here. The song is presumably about the lamb, Christ, the lamb of God (see John 1:29), and as such, it is both sorrowful and joyful, for Jesus died on the cross to atone for human sin and opened the gates of heaven. The lamb, an image that comes from the Old Testament Passover and sacrificial rituals, is a symbol of Christ.

We might wonder, too, about the identity of the child. The child asks for a song and then weeps. This child clearly knows the story well and is affected by it. We may reflect that perhaps the child also represents, or even is, Christ, asking the speaker to tell His own story, not so much for His benefit as for the speaker's. He continues to weep, partly for joy and partly, perhaps, for those who have not yet heard the song.

The poem “The Lamb” also blends the images of lamb, child, and Christ. The speaker is a child, filled with wonder and innocence. He speaks to a little lamb, asking the animal if it knows who made him. The Creator, the speaker says, “calls Himself a Lamb.” He even “became a little child” like the speaker. They are both, child and lamb, called by His name. He is the ultimate lamb, the ultimate child, from whom all others lambs and children receive their characteristics, especially their innocence.

All three, lamb, child, and Christ, are images of innocence. Christ is the perfect image, of course, for He is the sinless one, God incarnate, and lambs and children in their own innocence point to Him and model this trait to the world.

Blake also uses lambs and children to symbolize joy, as he does in “The Little Black Boy” when he speaks of the lambs rejoicing and God's children rejoicing around His tent. The lamb can also represent peace, for in “Night,” the speaker lies down beside a lamb and sleeps in peace, thinking of “Him who bore thy name.”

William Blake connects the image of the lamb and the child with Christ to emphasize the theme of innocence in the first section of his Songs of Innocence and Experience.

Lambs are a common Christian symbol because of the belief that Christ was a holy sacrifice sent to redeem the sins of humanity. In the Gospel of John, Christ is referred to as the lamb of God for this reason, calling back to Jewish traditions of animal sacrifice. The meekness of the lamb is also meant to represent the gentleness of Christ. It is much the same with the image of the child: Christ is often depicted as an infant in art in order to emphasize his sinlessness. Christ also says in several of the gospels that only those who "become as children" can enter the kingdom of heaven.

Blake most fervently plays with the connection between these three figures in "The Lamb." Here, the speaker is a small child telling a lamb about God. At the end of the poem, the child says the following regarding Christ:

He is called by thy name,

For he calls himself a Lamb:

He is meek & he is mild,

He became a little child:

I a child & thou a lamb,

We are called by his name.

The child is emphasizing an affectionate parallel between creation and God. If God created lambs and children—both innocent and guiltless—and this same God chose to be called a lamb and born into the world as the Christ child, then God and reality are fundamentally good. It is a profound assertion from such a young speaker, even if the poem's companion piece, "The Tyger," complicates it with the presence of violence and evil in the world.

The lamb, the child, and Christ are mentioned or alluded to several times in Songs of Innocence and Experience.

The lamb and the child are both common symbols for Jesus Christ. John the Baptist refers to Jesus as "The Lamb of God." In Christian art throughout the ages, Jesus is often depicted as a baby or a young child. Infancy and childhood represent innocence and being free of sin. William Blake was very spiritual and most of his poems deal with Christian faith to some degree. Blake had religious visions when he was a child and although he was a devout Christian, he had his own views on the religion, some of which were unorthodox at his time. Blake was opposed to the strict abstinence of his time. He also felt that childhood should be a time of joy and discovery, and that children should be outside playing instead of attending strict schools. Jesus was very important to Blake as the mortal iteration of God and a spiritual guide in his life.

In the first poem of Songs of Innocence and Experience, "Introduction," Blake introduces the child, symbol of innocence and of Jesus, enjoying interacting with nature: "On a cloud I saw a child." The child is on a cloud to give him spiritual presence, and to put him outside with nature, where Blake felt children ought to be. The cloud also symbolizes Heaven, since Heaven is supposed to be up above the earth like the clouds. Then the same poem introduces the lamb, a symbol of Jesus: "‘Pipe a song about a Lamb!’" (said by the child). In this quote, the word "lamb" is capitalized. This capitalization indicates that it is not just any lamb, it is the Lamb of God. The words "God," "Bible," and pronouns or words that symbolize God or Jesus are always capitalized.

The next poem, "The Shepherd," also mentions the lamb. The shepherd in this poem is Jesus, and the sheep are His followers.

The poem "The Lamb" in Songs of Innocence is very important. In this poem, the narrator is talking directly to the lamb, asking it if it knows who made it. Of course the answer is that God made everything and all creatures. This is the poem that clearly indicates the link between Jesus, the lamb, and the child in the following lines:

He is callèd by thy name,
For He calls Himself a Lamb.
He is meek, and He is mild,
He became a little child.
I a child, and thou a lamb,
We are callèd by His name.

You can see that the pronouns are capitalized and the word "lamb" is capitalized, which shows that this passage is referring to God/Jesus (Blake believed in the Holy Trinity— that God, Jesus, and the Holy Ghost are three aspects of one being).

I hope this explains the connection between the lamb, the child, and Jesus. If you want to learn more about Blake and Songs of Innocence and Experience on eNotes, click here.