The conception of an entity must be rejected, because it is metempirical and unverifiable, § 34. The conception of a force must be rejected, because it is irreconcilable with any definite idea we have of force. What the term Force signifies in Physics and Chemistry, namely, mass animated by velocity, or _directed pressure_, which is the activity of the agent,--is precisely that which these vitalists pertinaciously exclude. They assume a force which has nothing in common with mass and velocity; which is _not a resultant, but a principle_; which instead of being a _directed quantity_, is itself autonomous and _directive_, shaping matter into organization, and endowing it with powers not assignable to matter. If this vital force has any mass at its back, it is a spiritual mass; if it is directed, the direction issues from a “Mind somewhere.” Now this conception is purely metempirical. Not only is it inexact to speak of Vitality as a force, it is almost equally inexact to speak of it as a property; since it is a term which includes a variety of properties; and when Fletcher assigns the synonym of Irritability, this at once reveals the inexactness; for beside this property, we must place Assimilation, Evolution, Disintegration, Reproduction, Contractility, and Sensibility,--all characteristic properties included in Vitality. 41. Having thus rejected the conceptions of entity, force, and property, we are left in presence of--1°, the organic conditions as the elements, and 2°, of their synthesis (in the state called organization) as the personified principle. Vital forces, or the vital force, if we adopt the term for brevity’s sake, is a _symbol of the conditions of existence of organized matter_; and since organisms are specially distinguishable from anorganisms by this speciality of their synthesis, and not by any difference in the nature of the elements combined, this state of organization is the “force” or “principle” of which we are in quest. To determine what Life means, we must observe and classify the phenomena presented by living beings. To determine what Vitality--or organization--means, we must observe and classify the processes which go on in organized substances. These will occupy us in the succeeding chapters; here I may so far anticipate as to propose the following definitions:-- 42. Life is the functional activity of an organism in relation to its medium, as a synthesis of three terms: Structure, Aliment, and Instrument; it is the sum of functions which are the resultants of Vitality; Vitality being the sum of the properties of matter in the state of organization.