When I say that the table, the tree, and so forth, are sensations of mine, there is contained in this, as contrasted with the method of representation of the ordinary man, an actual extension of my ego. And so, too, upon the emotional side, such extensions actually occur; as for the virtuoso, who possesses as perfect a mastery of his instrument as he does of his own body; for the skilful orator in whom the eyes of an audience converge, and who controls the thoughts of his hearers; for the energetic politician who directs with ease his party; and so on. In conditions of depression, on the other hand, such as nervous people often have to endure, the ego contracts and shrinks. A wall seems to separate it from the world. * * * * * The ego is not sharply defined, its limits are very indefinite, and arbitrarily displaceable. Only by mistaking this, and by unconsciously narrowing these limits, as well also as by enlarging them, do metaphysical difficulties, in the conflict of points of view, arise. As soon as we have recognised that the supposed unities "body" and "ego" are only make-shifts for a _provisional_ survey and for certain practical ends (that we may apprehend bodies, protect _ourselves_ from pain, and so forth), we are obliged, in many thorough-going scientific investigations, to abandon them as insufficient and inappropriate. The opposition between ego and world, sensation (or phenomenon) and thing, then vanishes, and we are brought to deal simply with the _connection and relation of the elements_ α β γ ... _A B C_ ... _K L M_ ..., for which indeed this very opposition was only a partially appropriate, imperfect expression. This connection is nothing more than the combination of those elements with other homologous elements (time and space). This connection science has simply to _accept_, and set itself aright with regard to it, without attempting to explain its existence. Upon superficial examination the complex α β γ ... appears to consist of much more _evanescent_ elements than _A B C_ ... and _K L M_ ..., in which two last the elements appear to be joined with _more stability_ and _in a more permanent manner_ (being joined to solid nuclei as it were). Although upon closer inspection the elements of all complexes appear as _homologous_, yet even in spite of the recognition of this fact, the ancient notion of an opposition of body and spirit easily creeps in. The spiritualist feels, at times, the difficulty of imparting the necessary solidity to his world of substance created by mind: the materialist is at a loss what to do when called upon to animate and endow with sensation the world of matter. The _monistic_ point of view that reflection and reason have evolved, is easily overcast by the older and more powerful instinctive notions. VII.