With Learning by Expanding (Engeström, 1987), the development of cultural-historical activity theory entered a new phase. The book articulated a variety of structural aspects that researchers using cultural-historical activity theory might look for when attempting to analyze concrete human praxis. These aspects are captured emblematically by a triangular representation that has been a main scaffold for many scholars in their effort to understand a theory quite alien, in its dialectical foundations, to that of Western theorizing. Yet some elements of it have not yet come to be appreciated. Thus, to understand practical activity and the participative thinking that accompanies it requires understanding “the regulating effect of emotion” (Leont'ev, 1978, p. 27), because the “objectivity of activity is responsible not only for the objective character of images but also for the objectivity of needs, emotions, and feelings” (p. 54).

Many scholars have focused only on the structural aspects of activity, its systemic dimensions (Roth & Lee, 2007). These scholars have not taken into account the agentive dimensions of activity, including identity, emotion, ethics, and morality, or derivative concepts, such as motivation, identification, responsibility, and solidarity – all of which are integral to concrete praxis and its singular nature. These “sensuous” aspects of activity come into focus only if the whole activity – not only its structural but also its agentive dimensions – is analyzed.