Paste a novel or other large piece of text in the text box, and motifator will find clusters of words that occur frequently together.
It's useful for finding themes, connected ideas, character qualities, parallels or motifs in a text -- though the interpretation is up to you.
Try it first with a text you know well, like Hamlet or The Great Gatsby, to get a sense for how it works.
This forms clusters of words that occur in close proximity to each other. In this case, close is about 100 words -- on the same page, but necessarily adjacent. Having established the closest N word pairs, it then uses an iterative algorithm to group them into clusters, where a new cluster is preferred over an old one if it has a greater degree of connectivity between all its members. Words are progressively shuffled between clusters until the (almost) best connected sets are found.
Try Project Gutenberg for more books (it helps to omit the prefatory Gutenberg material when copying them).