If the reader chooses to formulate for himself a working definition based on the above remarks he is at liberty to do so, but he may take for granted that nobody else will accept it. However, he will have gained, at any rate, a clearer conception of the matter than he would perhaps have gathered from any dictionary. We have seen that mazes and labyrinths may be roughly divided into two types as regards the principle of their design, namely, into _unicursal_ and _multicursal_ types, or, as some say, into "non-puzzle" and "puzzle" types respectively. The word "unicursal" has hitherto been chiefly used by mathematicians to describe a class of problems dealing with the investigation of the shortest route between two given points or of the method of tracing a route between two points in a given figure without covering any part of the ground more or less than once (_e.g._, the well-known "bridge" problems), but there is no reason why we should not apply the adjective "unicursal" (= "single course" or "once run") to denote those figures which consist of a single unbranched path, using the term "multicursal" as its complement, or antonym. We must not draw too hard a line between these two types; for instance, we could not reasonably insist that the turf maze at Wing (Fig. 60) is multicursal simply on account of the dichotomy of its path to form the central loop. Where the loop is itself relatively large and complex, as in the Poitiers example (Fig. 55), there are better grounds for doing so, but it is plain that in such cases the point is one to be decided by common-sense. Let us consider a little further the various _forms_ of labyrinth design and make some sort of a classification. In the first place we may observe that a labyrinth (using this word, for convenience, as embracing "maze") may be arranged in one plane, as we commonly see it on a sheet of paper, or it may be disposed in two or more intercommunicating planes, like the Egyptian labyrinth or a block of flats. We may thus classify all labyrinths, for a start, as either two-dimensional or three-dimensional. As the vast majority belong to the first class and as, moreover, every subdivision of the first class may be applied equally to the second, we need say no more concerning the latter except to remark that the complexity of a garden maze may be greatly increased, if desired, by introducing tunnels or bridges, thus converting it into a three-dimensional maze. Another general grouping of labyrinths would be into "compact" and "diffuse" types, the former having, in a typical case, the whole of its area occupied by the convolutions of its path and its bounding walls, the latter having spaces between the bounding walls of the various sections of the path, such spaces having no communication with the path itself. Amongst unicursal labyrinths the Alkborough specimen (Fig. 59) exemplifies the compact type and the Pimperne maze (Fig. 63) the diffuse type.