Earlier in John 1:29 John the Baptist's statement to the crowd of people was, "Behold the Lamb of God that takes away the sin of the world." In verse 36 he simply says, "Behold the Lamb of God." It was not necessary to repeat the whole statement as they knew what he meant. They were spiritual men. One was Andrew and the other, though unnamed, I believe was John. The moment John the Baptist said it, they left him and followed Jesus. Andrew could not wait to tell his brother Simon who later was named Cephas (meaning a stone) which he would keep the three years of discipleship. This name is also translated Peter in the Greek language.
Now do we know Jesus as the Lamb of God that takes away the sin of the world? Have you realized that He can take your sin away too? Now if this is true of you, have you brought someone else to Jesus? Have you noticed how eager Andrew was to tell someone the news?
Andrew is mentioned only three times in the book of John. This time is the first. Then he finds the boy with five loaves and two fish. Then in John13:21,22 when Phillip was approached by Greeks he first told Andrew and together they told Jesus. To me this presents Andrew as a people person. I want to be that too! Do you?