 In view of such difficulties, some have argued that B 109 (= D 207) implies a more general notion than sense perception. If opôpamen includes understanding and knowledge (as it seems to in the case of Love and Strife), then Empedocles is not talking about the meeting of external and internal elements. Rather, he implies a more abstract operation in which we acquire an intellectual grasp of the roots and the forces and do not just perceive them (see Kamtekar 2009). However, two recent studies that focus on the perception of color imply that B 109 (= D207) describes sense perception (Ierodiakonou 2005 and Kalderon 2015: 1–16).