Foucault was not a system-builder, but a philosopher of the present. No matter how abstract or erudite his topics of inquiry, he was fundamentally concerned with the changing world about him. Most philosophers start (if only implicitly) with a point of view on truth and the metaphysical nature of things. Foucault started with a situated vision on how things are changing today. Foucault would ask how he might contribute to these changes so that he too was changed by the experience. This was the point of doing philosophy, for Foucault: to learn to engage with change in such a way that one was transformed in the process.
Tim Rayner at Philosophy for Change. Epic change: how to make ‘today’ a moment of vision (via protoslacker)