Sec. 28. As we proceed, we shall find survivals of old plans, even at an advanced period in the middle ages, which prove that progress in architecture was by no means of an uniform kind. Builders in remote, and especially in hilly, districts, from Saxon times to the present day, have naturally restricted themselves to plans which require as little cost as possible to carry out. Local building material is also an important consideration. In districts where good building stone is to be obtained on the spot, or where money is plentiful and water carriage is possible, the development of plan is naturally rapid, and every fifty years or so, additions to churches will be made in which the old plan will become entirely transformed. In woodland districts, the plan will be controlled to no small extent by the requirements of timber construction. In such regions, Saxon churches were probably built of wood. The only wooden church of Saxon times which remains is that of Greenstead in south Essex, with a rectangular chancel and aisleless nave constructed of vertical logs placed side by side, and framed originally into a timber plinth. However, it may be stated as a general rule, that, whatever may be the helps or hindrances to development provided by local materials, the real starting-point of the parish church plan of the middle ages is in every part of the country an aisleless plan; and that this plan consists either of a nave and chancel with a longitudinal axis, or of a nave and chancel whose longitudinal axis is intersected by a transverse axis across transepts. Variations, no doubt, occur; but these will never carry us far from one or other of these fundamental plans. The aisled basilica of the continent found no scope for itself in Saxon England; and it was through an interval of aisleless building that the aisled plan eventually became acclimatised, and then in a form which bears only a superficial kinship to the basilican plan. CHAPTER III THE AISLELESS CHURCH OF THE NORMAN PERIOD