The Manual of Dionysius is an abstract of this wide scheme, but is still very comprehensive. The copy of it seen by Didron was one belonging to a monk of Sphigmenou named Joasaph, who was himself a painter. It was "loaded with notes added by himself and his master, which in course of time would be incorporated, according to immemorial custom, in the text." In this way, indeed, the Manual has grown to what it is at present. A transcript of it may probably be found in every monastery belonging to the Greek Church. Another monk named Macarios, also a painter, had a fine copy of it laid open in his atelier, and his pupils read from it in turn, whilst the rest painted according to its directions. For the scheme itself we must refer the reader to the second volume of Didron's _Christian Iconography_, p. 193. Unfortunately the transcriber did not think it of sufficient importance or relevancy to copy the first part, as being purely technical and dealing merely with the art of painting. The scheme, therefore, only contains the part relating expressly to iconography. It is to be regretted, too, that this part also has been in some places considerably abridged, as dealing with Greek art and martyrology more copiously than, it was thought by the translator, would be interesting to English readers. There are numerous good and reliable introductory works dealing with early Christian art, besides the greater treatises to which the student who wants to pursue this line of research shall be directed later on. But there is another of these original manuals to which we must call attention, as especially dealing with the practice of monastic artists in the twelfth and following centuries. The one to which we now refer is quite distinct from the Greek Manual which we just mentioned, and by way of contrast may be called the Latin Manual as being originally composed in that language. Moreover, as the Greek Manual formed the guide and _vade mecum_ of all the painters of the Greek Church, so this Latin one became the indispensable monitor in all Latin foundations. Its origin was German, and said to be the compilation of a Benedictine monk who is variously spoken of as Rutgerius, Rugerius, Rotkerius, etc., and assigned by different editors and critics to either the eleventh, twelfth, or thirteenth centuries. Probably we shall not be far wrong in placing him about the middle of the twelfth. The treatise is known as _Diversarum Artium Schedula_, and the compiler of it calls himself simply _Theophilus presbiter humilis_, which, of course, records nothing but his personal modesty.