The overriding theme of the book is whether animals have consciousness and a soul, just as humans do. Montgomery explores this throughout the book, as she observes the behavior of octopuses when interacting with her and her friends, and examines empirical research about them. She takes her cue from Thomas Nagel’s famous 1974 essay entitled “What Is It Like to Be a Bat?” and tries to learn what it is like to be an octopus. Some of the questions she attempts to answer are the following: Do octopuses have a sense of self? If so, how do they perceive it? Do they have a sense of other beings? Do they have a soul?

Montgomery provides ample evidence that octopuses recognize and have varying attitudes toward different people. They respond to the touch of humans in various ways, able to distinguish them both through sight and “tasting” people’s skin with their suckers. One study Montgomery notes had two people, unknown to the octopuses and dressed identically, exhibit different behavior toward the octopuses: One person fed the octopuses, while the other person brushed the octopuses with a prickly, irritating stick. The animals soon learned the difference, moving toward the feeder and away from the brusher.