Architecture being progressive, it was only by the gradual development of one style from another that the art was enabled to advance with social progress, the literature and other arts of the country. The transition from the Norman to the Early English style may be ascribed to a period somewhat earlier than the 12th century, when a great change in the construction of the arch began to manifest itself. Alone, however, the form of the arch is no real test, for many pure Norman works have pointed arches. The square abacus may be taken as the best test. In its incipient state the pointed arch exhibited a change of form only, whilst the accessories and details remained the same as before; and although this change gradually led to the Early Pointed style in a pure state, with mouldings and features altogether distinct from those of the Norman, and to the general disuse, in the 13th century, of the semi-circular arch, it was for a while so intermixed as, from its first appearance to the close of the 12th century, to constitute that state of transition called the semi-Norman. [Illustration: Windows showing the Origin of Tracery.] CHAPTER IV. THE EARLY ENGLISH STYLE. The origin of what is loosely called Gothic architecture--which is generally considered to include the styles, with their transitions, from Early English to late Perpendicular, or Tudor-Gothic--is not free from obscurity, but it is certain that it began to be employed in ecclesiastical edifices about the time that the Goths settled in Italy, although all the available evidence goes to prove that the style originated and underwent its earliest developments in the north-west of Europe, and penetrated by slow degrees to the south and east. England was somewhat later than France in introducing this style of architecture, our earliest purely Gothic building being Salisbury Cathedral, begun in 1220, although the choirs of Rievaulx and Fountains Abbey were commenced a few years earlier. The Early English style in its earliest developments is nowhere seen to better advantage than in Salisbury Cathedral, and in its very latest forms at Westminster Abbey, the period of time being chronologically measured by the reigns of Richard I., John and Henry III. [Illustration: An Early English Arch. Rochester Cathedral. _Photograph Eastmead._] Most of our Gothic buildings were carried out under the supervision of a master-mason, but the most subordinate workman was left plenty of scope within reasonable limits for whatever artistic individuality he possessed, and the enrichments and ornaments of the Gothic era point out the noble aim, the delicate and graceful thought, the refined and exquisite taste expended upon every portion of their buildings by these Gothic masons. [Side note: The Pointed Arch.]