The following pages have as their aim a discussion and demonstration as to how Escher achieved some of his effects or devices. Concerning some of his tessellating-based prints, what I term as three distinct types of ‘devices' are used, either singly or in combination: (i) Black, Grey and White, (ii) Development, (iii) Counterchange. Although all three terms are to a degree self explanatory, clarification as to specifics should be established.

Development
Here the outline of the motif increases in its angularity from its underlying geometrical tessellating framework to a fully developed state. A typical example being just after the beginning of Metamorphosis I, with squares developing into lizards.

Counterchange
Here the motifs ‘exchange' foreground and backgrounds. Typical examples being Plates II, Nos 1, 2 and 3, and II-IV in Regelmatige vlakverderling.

How he achieved the effects
Of some importance is to exactly how Escher achieved these effects, as they are critical to the ‘success' of the prints. Indeed, they are indispensable. However, although of fundamental importance, for whatever reason, all of these aspects have not been discussed or disclosed by Escher (beyond the merest mention in The Graphic Work of M. C. Escher) or indeed by any other publication. (For such a lack of material, see essay * where this is discussed in detail). Consequently, such effects have not appeared with his successors, presumably due to lack of understanding a ‘general theory' of how to undertake such matters. Therefore, as a considered study of the theory underlying these aspects is thus considerably overdue, I thus show,in the following pages, for what I believe to be the first time, how Escher probably went about such matters. Of necessity, I emphasise the word probably, as not a single example of Escher's ways and means has been published to my knowledge, in contrast to studies of ‘spatial constructions' and so consequently, the exact methodology thus remains unknown. If anyone does indeed has information of this, I would be more than pleased to receive details.

As such, this is intended as a practical guide, of which the following is taken from my own studies, suitably presented 'as appropriate' rather than an all-encompassing general theory detailing every last aspect. However, this is not to say that what follows is not systematic or thorough in approach. Indeed, it is most detailed to what I consider would be appropriate degree. Unfortunately, the process of putting further examples on show is somewhat inconvenient in terms of the time required, and so consequently any further examples I propose to put on hold to the neat update. However, due to the time factor involved, bearing in mind that this is meant to be a practical guide, I would be interested in hearing if any of this is of actual use or interest. This being so, to gauge the degree of interest, further updates will depend on the reader in that only upon request (by e-mail) will this then appear.