Modern theory of rent extend or improved the ideas further given by Marshall Marshall theory of rent is based on quasi rent and modern economists further improved the idea which is based on demand and supply
Modern theory of rent sees land from the stand point view of an individual where as marshal theory of rent views land from the stand point of society as a whole. In Marshall theory land has no alternative use hence transfer earnings but in modern theory land has alternative uses. in Marshall rent does not enter into price but modern theory shows that rent is not price determined it is price determining