The author presents a general discussion of a local isometric embedding of the spherically-symmetric Stephani model in relativistic cosmology (this cosmological model is the only conformally flat perfect fluid solution of the Einstein equations that is not expansion-free, has non- zero density, and can be embedded in a five-dimensional flat pseudo- Euclidean space). The paper contains six major sections: an introduction, a review of general properties of the Stephani model, simple examples of special subclasses, e.g. the de Sitter models, strictly inhomogeneous models, conditions necessary to obtain the Friedman limit, a summary/conclusions; and three appendices dealing with the embedding and mathematical technicalities. The author’s exposition contains an unusual wealth of detail – including excellent figures – and one is tempted to say that the methodology is almost as valuable as his results. It is required reading for mathematical cosmologists.