Perhaps the most perplexing problem that has troubled curriculum theorists is how to account for quality in human experience, for experience is an extraordinarily difficult thing to pin down and to theorize about. Experience seems to have both reflective and nonreflective dimensions and to consist of an ever fluctuating mixture of inseparable reactions sometimes roughly classified as cognitive, affective, and psychomotor. In short, "experience" seems to be a somewhat vague but all-embracing term that designates an amazingly wide and complex set of human phenomena comprising the most basic material of which all education consists. Thus we might expect to find curriculum theory attempting to develop some comprehensive conceptions about the nature of experience.