ABSTRACT
Words such as 'Matter', 'material object', or 'material event' refer to cognitum groups and sequences which follows each other in a certain type of pattern, or with a certain kind of regularity, namely, the type codified as what people call the laws of material physics. Words such as 'Mind', 'mental object', or 'mental event' are cognitum sequences which follows a different sort of pattern, to wit those codified in the laws of psychology, so far as these are at present understood. No difficulty of principle about understanding how mental and material cognitum systems may interact and influence one another, just as there is no difficulty in understanding how Greeks organized in line of phalanxes can interact with Romans organized in echelon of cohorts, however difficult it might be to forecast the precise course and outcome of the conflict.
