301. Sensible and Rational Appetites. -- A great law governs the entire appetitive life: "Nihil volitum nisi praecognitum ". Every appetition presupposes the knowledge of the object desired. The sensible appetite is the tendency of the organism towards a concrete object presented by the senses as a concrete good. Intensity of appetite gives rise to the sensible passions -- a fruitful field for observation and classification, and one in which the scholastic genius gave itself free scope. The rational appetite, or the will, acts consequently to the presentation of an abstract good. Here also the motive or mainspring of the appetitive tendency is the perfection of the appetitive being: "bonum est quod omnia appetunt".^{1} Some volitions are free.

{1} As for pleasure and pain they follow upon appetition, reside formally in the appetitive faculties, but may have their source in any conscious activity whatsoever.