For me, the children's book that had the biggest impact on my life was "Horton Hears a Who" by Dr. Seuss.
As a child I was always bending low to examine a small creature on a flower or blade of grass, and this book spoke to something so intuitive inside me. The idea that there could be a whole world that is unseen by the naked eye, existing on something so small as speck of dust, opened my imagination wide.
And to this day I love the message this book conveys: "A person's a person, no matter how small!" As a library technician in school libraries I often have this running through my head when a young student has something interesting to tell me about their day, or they are excited about something they are doing at school. Their words and ideas are just as important as someone bigger then them. Although "Horton Hears a Who" was first published in 1954, the messages of kindness, care and the 'power of one' are still relevant and still so very important.