Passage 1
And yet our consciousness is there, and has in all probability been evolved, like all other functions, for a use — it is to the highest degree improbable a priori that it should have no use. Its use seems to be that of selection; but to select, it must be efficacious. States of consciousness which feel right are held fast to; those which feel wrong are checked. If the ‘holding’ and the ‘checking’ of the conscious states severally mean also the efficacious reinforcing or inhibiting of the correlated neural processes, then it would seem as if the presence of the states of mind might help to steer the nervous system and keep it in the path which to the consciousness seemed best. Now on the average what seems best to consciousness is really best for the creature.
Cognition, attention, and judgmentFree will and automatismselection and judgment · advancesautomatism · rejectsNature and evolutionScientific or empirical evidenceEnlarges autonomyIndividualMind and body
The Briefer Course makes selection consciousness’s evolutionary function: holding and checking mental states are proposed as causally steering neural activity.
Chapter VIII, “The Functions of the Brain,” pp. 103–04