Merleau-Ponty on the History of Philosophy

I recently acquired Merleau-Ponty's The Incarnate Subject: Malebranche, Biran, and Bergson on the Union of Body and Soul, the notes from a lecture course he gave at Ecole Normale Supérieure in Paris and the University of Lyons to prepare students for the qualifying exam for the agrégation in philosophy. In it he has an interesting statement on how one does the history of philosophy:

The objectivity of the history of philosophy is only found in the practice of subjectivity. The way of understanding a system is to ask of it the questions with which we ourselves are concerned: it is in this way that systems appear, with their differences, and bear witness whether or not our questions are identical to those which their authors themselves posed.

The history of philosophy is a confrontation, a communication with systems, analogous to that which we are able to have with persons. Even though philosophers may choose, their choice is always accompanied, as if in the margins, by a suspicion of what is overlooked. All consciousness of a thing is, at one and the same time, consciousness of what is not this thing. Each philosophical choice stands out in relief against the background of what was not chosen, and it is in this way that philosophers communicate; it is the residue which maintains the dialogue among persons and, consequently, the history of philosophy.