It is while living with Jubal, that Mike begins his quest to "grok" the human condition. Grok is a basically untranslatable Martian term but it is a measure of the novel's impact that the word has sufficient gravitas to be defined in several dictionaries. For instance, The American Heritage® Dictionary of the English Language defines it as "to understand profoundly through intuition or empathy." That's about as close as you can get to a definition, and as is readily stated in the novel, you really have to have grown up Martian to truly Grok the word. Heinlein writes a wonderfully convoluted tale, creating an incredibly rich weave from the many threads that run through the story. For instance, he creates a legal history upon which Mike's claim to be defacto owner of Mars (and incidentally much of the moon) is based, and this further allows him to touch on the moral ambiguity of laying claim to an already inhabited planet; shades of settlers encroaching on the land of native American Indians. Indeed, the entire book is a minefield of social commentary and discussion, much of it as muddled as it is profound.

The muddle is in fact one of the charms of the book. The characters grow and evolve significantly as the story progresses, and Mike is not the only one to learn what it is to be human, though the conclusions will not be to everyone's liking.