1. A method of locating relevant documents within a universe of documents, the documents of said universe having been classified so that each document in the universe has a fingerprint, said fingerprint comprising a list of weights associated with particular topic categories in a classification system, each of the weights representing a degree to which the document relates to the particular topic category that the weight is associated with, the weights obtained automatically from a computer program, the method comprising: identifying a first piece of text, creating a fingerprint for said first piece of text, the fingerprint comprising a list of weights associated with particular topic categories in the classification system, each of the weights in the fingerprint for said first piece of text representing a degree to which the first piece of text relates to the particular topic category that the weight in the fingerprint for said first piece of text is associated with, the weights in the fingerprint for said first piece of text obtained automatically from a computer program, searching all or a portion of the universe of documents by comparing the fingerprint for the first piece of text with the fingerprint for each document in the all or a portion of the universe of documents, ranking the all or a portion of the universe of documents based on a degree to which a document has a mathematical overlap with the fingerprint of the first piece of text.