Introduction
This essay is concerned with discussing the merits for tessellation purposes of different types of motifs, of which the choice of motifs can be essentially separated into two distinct entities, namely that of animate and non-animate motifs.

Animate or Non-Animate Motifs - Generalised
As such, the choice of motifs can be separated into two distinct entities, namely that of non-animate and animate motifs. Of some considerable importance is an appropriate choice, as otherwise much time can be wasted in a futile pursuit of an unsuitable motif, with little or no chance of success. Although there are a great number of potential motifs per se, it is possible to reduce greatly this to permit a practical consideration, and so I describe the choice as of two distinct types, namely that of animate and non-animate motifs.

So, which of these two types are more suited for tessellation purposes? As such, it may be thought that there is no intrinsic difference between the two categories, with the likelihood that a animate motif (say, bird) or a non-animate (say, car) or would be equally suitable choices, both possessing indentations of the sort that would permit tessellations to be so composed. However, in practice, there will be found to be a world of difference, with the examples chosen as illustrations of two extremes - birds can be seen to abound, whereas cars are rarely found. (A noticeable assistance in comparing the occurrence and frequency of specific motifs is being provided by Patrick Snels, who is currently compiling a database of tessellation motifs (albeit this is still under construction), derived from people who are composing representational tessellations of a more or less worthwhile standard.) Put simply, by far the easiest type of motif to tessellate is with the animate type. In contrast, inanimate motifs are most trying, if not generally impossible to succeed with these, at least to an acceptable degree. Now, why should this be so? Although there is a wide choice of both animate and non-animate motifs, it is possible to generalize without examining every conceivable motif. So, put simply, the difference between animate and non-animate motifs is that the former permits variation of line, whereas the latter does not. Such variation of line is the crux of the issue. For example, a bird can be of have a long or short wing span, a long or short neck, a long or broad tail - all these elements thus possess variability. In contrast, a car is 'shape specific'. Although variations of cars exist, with different models, such as family or sports cars, the basic shape essentially remains alike. Consequently, as there is less variation of line, cars are not readily suitable.

Other People’s Choice of Motifs
Of interest is to what extent other people use animate and non-animate motifs. Here, I take three leading tessellation people, namely Escher, Nakamura, and myself, and examine their tessellations for choice of motif.

Escher's
Upon examining Escher's 137 periodic drawings, these mostly, overwhelmingly, consist of animate motifs. Conspicuous by their absence are those of a non-animate nature. Although Escher did include the occasional non-animate example, this was very infrequent. Indeed, only eight of his drawings possess this type, and indeed, six of these are accompanied with animated motifs. Did Escher purposefully restrict his interest in tessellation to animate forms to the exclusion of non-animate examples? Almost certainly, no. Most probably, he quickly found that the animate type were far more suitable for his purposes, and so thus naturally concentrated on these. Only on a handful of occasions were non-animate motifs used, and even here, when so used these were generally in conjunction with animate motifs or consisted of organic motifs from the plant world. Specific instances include:

No.30, of fishes and boats

No.42, of two different types of shells, with starfish

No.43, of flowers and leaves
No.64, of leaves
No.72, of fishes and boats
No.100, of a 'winged letter'
No.122, of fishes and boats
No.123, of fishes and boats

Interestingly, without exception, all these examples are not 'shape specific', and so thus remain likely 'possibilities' for tessellation purposes, consisting as they do of gently undulating lines. Therefore, although not explicitly stated, Escher by default emphatically omits such non-animate examples.

Nakamura
Upon examining Nakamura’s 250+ periodic drawings, these all consist of animate motifs. Conspicuous by their absence are those of a non-animate nature.

Bailey
Of interest is my own work. Again, as with Escher and Nakamura, non-animate examples are generally disregarded. Indeed, on the website, consisting mostly of definitive drawings, not a single example of this type can be found. Only on a few occasions have such examples been used, such as with a telephone, but even here the distortion involved in such a 'shape specific' object is such that I do not consider it worthwhile to proceed beyond its study state.

Summary
Therefore, the inference should be obvious - animate examples are in essence to be the sole choice of motif. Quite simply, non-animate examples are unsuitable for tessellation purposes. Not only are these difficult to tessellate, even when so accomplished, even to an arbitrary 'acceptable' quality, the inevitable distortions involved render the motif as of an inferior standard. In contrast, animate forms can be so shown that are so lifelike that taken in isolation no apparent difference between a tessellation and a 'normal' drawing can be discerned, the ultimate accolade for a tessellation.