It is suggested that considerable clarification in cosmology results from the hypothesis that continual creation of new matter is a property of existing matter depending upon its physical state. Accordingly, it is envisaged that effectively all matter is in galaxies and that continual creation simply promotes the growth of galaxies; any galaxy, however, may occasionally eject a fragment of itself that becomes the embryo for the growth of a new galaxy. A steady-state model universe may be constructed in conformity with this picture. The proposed view appears to be in better accord with general physical concepts than that of current steady-state cosmology, where the rate of continual creation is taken to be effectively uniform in space and time and independent of already-existing matter. The new suggestion simplifies the problem of galaxy-formation; in requiring no important quantity of intergalactic matter, it does not conflict with available observational evidence. If the suggestion could be given a more quantitative formulation, it would apparently show whether we should see a universe composed of ordinary matter, or one composed of galaxies made of ordinary matter intermingled with galaxies made of anti-matter, without demanding any special mechanism for separating matter and anti-matter. By discarding the hypothesis of a rate of creation that is a universal constant, cosmology based on continual creation becomes a more flexible concept; it may accommodate the author's suggestions regarding uncertainty in cosmology.