1. A method comprising: identifying multiple concept-units from a multi-language document corpus, a particular concept-unit including a set of documents in different languages describing a particular concept; modeling the concept-units of the multi-language document corpus to create a generative model, wherein the generative model represents at least: (a) a plurality of universal topics, each of the universal topics being defined by a plurality of topic word distributions corresponding respectively to the different languages; (b) a topic distribution for each concept-unit, wherein the documents of any single concept-unit are constrained within the generative model to share a common topic distribution; inferring the plurality of universal topics from the documents of the concept-units based on the generative model.