The philosophical study of the first principles of human thought and their value as knowledge. It is also called epistemology and treats of the criteria or norms for determining the truth. These norms are both objective and subjective. Objective criteria are intrinsic evidence, where available, on divine or human authority, where truth is otherwise unavailable. Subjective criteria are the human faculties of knowledge, which faith tells the believer must be assisted by divine grace for the acceptance of revelation on God's authority.