Neither do we feel sure that, in such a question as this, definitions do not lead to confusion rather than to clearness. When short, they are vague and obscure, and only acquire precision through distinctions and developments which have to be discussed at length; and again they generally lead, on one hand or the other, either to objections or reservations. _Omnis definitio in jure periculosa_, says an old maxim, which is certainly true in matters of art. Why should we attempt, unless we are obliged, to define terms which awake sufficiently clear and distinct ideas in all cultivated minds? No satisfactory definition has ever been given of the word _architecture_, and yet, when we use it, every one knows what we mean. Architecture, sculpture, painting, each of these sounds has a precise meaning for those to whom our work is addressed, and we may say the same of certain other expressions, such as _industrial arts_, _decoration_, _style_, _historical painting_, _genre painting_, _landscape painting_, which will often be found in our pages. We must refer those who want definitions of these phrases to the _Grammaire des Arts du Dessin_ of M. Charles Blanc and kindred works. It will suffice for us that these words should be taken in the ordinary meaning which they bear in the conversation of cultivated men. If our ideas of art and its different branches diverge here and there from those which are commonly received, those divergencies will become evident, and will be discussed and justified to the best of our ability as the work proceeds. But on all occasions we shall do our best to avoid the abstract and pedantic terminology which makes Ottfried Müller's first chapter so difficult to read. * * * * *