Generally speaking, the onlooker, with his wider field of vision, regards the _ultimate outcome_ of an activity as what it is more really doing; and _the most previous agent_ ascertainable, being the first source of action, he regards as the most real agent in the field. The others but transmit that agent's impulse; on him we put responsibility; we name him when one asks us 'Who's to blame?' But the most previous agents ascertainable, instead of being of longer span, are often of much shorter span than the activity in view. Brain-cells are our best example. My brain-cells are believed to excite each other from next to next (by contiguous transmission of katabolic alteration, let us say) and to have been doing so long before this present stretch of lecturing-activity on my part began. If any one cell-group stops its activity, the lecturing will cease or show disorder of form. _Cessante causa, cessat et effectus_--does not this look as if the short-span brain activities were the more real activities, and the lecturing activities on my part only their effects? Moreover, as Hume so clearly pointed out,[99] in my mental activity-situation the words physically to be uttered are represented as the activity's immediate goal. These words, however, cannot be uttered without intermediate physical processes in the bulb and vagi nerves, which processes nevertheless fail to figure in the mental activity-series at all. That series, therefore, since it leaves out vitally real steps of action, cannot represent the real activities. It is something purely subjective; the _facts_ of activity are elsewhere. They are something far more interstitial, so to speak, than what my feelings record. The _real_ facts of activity that have in point of fact been systematically pleaded for by philosophers have, so far as my information goes, been of three principal types. The first type takes a consciousness of wider time-span than ours to be the vehicle of the more real activity. Its will is the agent, and its purpose is the action done. The second type assumes that 'ideas' struggling with one another are the agents, and that the prevalence of one set of them is the action. The third type believes that nerve-cells are the agents, and that resultant motor discharges are the acts achieved. Now if we must de-realize our immediately felt activity-situations for the benefit of either of these types of substitute, we ought to know what the substitution practically involves. _What practical difference ought it to make if_, instead of saying naïvely that 'I' am active now in delivering this address, I say that _a wider thinker is active_, or that _certain ideas are active_, or that _certain nerve-cells are active_, in producing the result? This would be the pragmatic meaning of the three hypotheses. Let us take them in succession in seeking a reply.