At the age of 31 while studying theology in the Jesuit School of Theology at Berkeley, a friend of Dan Schutte asked him to compose a song for the upcoming diaconate ordination Mass, according to "Faith." His friend asked him to “include the images of God, the light of Christ and the bread and wine.”
Schutte had no idea how to do this, but he turned to the scriptures, where he based his hymn on Isaiah 6:8 and I Samuel 3:4. In the story, Samuel heard a voice calling in the night. Thinking it was his master, Eli, Samuel got up three times to answer the call. The third time, Eli realized the voice was from God “So Eli told Samuel, “Go and lie down, and if he calls you, say, 'Speak, LORD, for your servant is listening.'” So Samuel went and lay down in his place. The LORD came and stood there, calling as at the other times, 'Samuel! Samuel!' Then Samuel said, “Speak, for your servant is listening,” I Samuel 3:9-10.
I love the haunting tune and the message behind it. It begins with “I, the Lord of sea and sky/I have heard my people cry/All who dwell in dark and sin/My hand will save/I who made the stars of night/I will make their darkness bright/Who will bear my light to them?/Whom shall I send?”
The refrain continues, “Here I am, Lord/Is it I, Lord?/I have heard You calling in the night/I will go, Lord/If You lead me/I will hold Your people in my heart.”
An international Catholic magazine, the “Tablet” conducted a survey, which found the hymn to be the readers' 63rd favorite. The National Association of Pastoral Musicians conducted a poll, which found it to be second among “songs that make a difference.” Then in 2019, United Kingdom residents voted it as their 10th favorite hymn.
Information provided by Wikipedia and an article in Faith.