Instead therefore of entering, as is usual in elementary works of this nature, into a detailed account of all the parts of an Ecclesiastical structure, a certain portion only of such a building has for this purpose been selected, and so exhibited in the garb in which it appeared at successive intervals of time, as to present to the reader a means of comparison that will enable him readily to apprehend the gradual change of form through which it passed from the Eleventh to the Sixteenth Centuries, and at once to recognise the leading characteristics of the several Periods into which it is here proposed to divide the History of our National Architecture. Having thus fixed these leading characteristics in his mind, he will then be in a condition to follow us hereafter, if he pleases, into the detail of the whole subject, and to become familiar with those niceties of distinction, the detection of which--escaping, as they do, the eye of the general observer--contributes so materially to the enjoyment of the study, and a perfect acquaintance with which is so absolutely essential to a correct understanding of the true History of the Art. That this mode of approaching the study of this subject is a convenient one, will probably be admitted by those who may remember the difficulties they encountered, in their early attempts to acquire a general conception of the scheme of the History of Church Architecture, as given in most of the manuals now in use; and the complexity of detail in which they found themselves immediately involved on the very threshold of their inquiry. It has been the practice in most elementary works on Church Architecture to derive the illustrations of the subject, indifferently from the smaller and the larger buildings of the Kingdom; and by implication to assign an equal authority to both. It will be readily admitted, however, that the History of an Art is to be gathered from its principal Monuments, and not from those the design or execution of which may have been entrusted to other than the ablest masters of the Period: in the choice, therefore, of the examples which have been selected to illustrate the series of changes which are described in the following pages, reference has been made principally to the great Cathedral, Abbey, and Collegiate Churches of the Kingdom, and occasionally only to some of the larger Parish Churches whose size or importance would seem to bring them under the above denomination. CHAPTER II. CLASSIFICATION.