Page:Theory of Mind of Roger Bacon.djvu/17

 With this introduction, Bacon is ready to define the Species. But for purposes of exposition, let us get before us at once a summary definition, and then look closely into the meaning of its several parts.

It is uniformly so, in the sense that it is the effect of a natural Agent acting in accordance with law and without variation. Always the first effect which the Agent produces is the Species; for, a natural Agent cannot now produce one “first effect” and again another. To be sure, the same Cause, or Agent, does produce different Effects; but the difference is to be sought in the things acted upon, and not in the Agent. For example, the sun illuminates the stars, melts the wax, hardens the clay, and warms the sense of touch; and it is the same “virtue” that acts upon all. But in each case the difference is in the Matter of the Patient receiving the Species; the Species, as first effect, is always the same, quite regardless of the nature of the Patient.

The significance of this characteristic of the Species for sense-perception is important, and Bacon calls especial attention to it. The Species of any given Agent is always Species-of-that-Agent; accordingly, whether it acts upon the external world or upon the senses, the Species as such is uniformly the same first effect.

It is the univocal effect of the Agent. An Agent may have many and various effects, but all save the first are equivocal or secondary effects. These differ from the univocal or primary effect in various respects. Thus, of the former there may be many, whereas of the latter there can be but a single one. Again, the univocal effect comes immediately from the Agent, whereas the equivocal effects are derived mediately through this. Finally, the univocal effect is essentially the same with the Agent, whereas the equivocal effects are in essence unlike the Agent. Still, the equivocal effects are predominant; they are the effects which Nature chiefly seeks. And obviously, too. For, did the action of the Agent stop with