two great domains of philosophical knowledge—_Theoretical_ or _Speculative Philosophy_, and _Practical Philosophy_. There are, in fact, two great domains into which the data of all human experience may be divided; and for each distinct domain submitted to philosophical investigation there will be a distinct department of philosophy. A first domain is the order _realized_ in the universe independently of man; a second is the order which man himself _realizes_: _things_, therefore, and _acts_. The order of the external universe, the order of nature as it is called, exists independently of us: we merely study it (_speculari_, θεωρέω), we do not create it. The other or _practical_ order is established by our acts of _intelligence_ and _will_, and by our _bodily action_ on external things under the direction of those faculties in the arts. Hence we have a _speculative_ or _theoretical_ philosophy and a _practical_ philosophy.(11) IV. DEPARTMENTS OF PRACTICAL PHILOSOPHY: LOGIC, ETHICS AND ESTHETICS.—In the domain of human activities, to the right regulation of which practical philosophy is directed, we may distinguish two departments of mental activity, namely _intellectual_ and _volitional_, and besides these the whole department of _external_, executive or bodily activity. In general the right regulation of acts may be said to consist in directing them to the realization of some ideal; for all cognitive acts this ideal is the _true_, for all appetitive or volitional acts it is the _good_, while for all external operations it may be either the _beautiful_ or the _useful_—the respective objects of the fine arts and the mechanical arts or crafts.