Hegel: The philosopher with the (one) big idea

GWF Hegel (1770-1831) wanted to construct nothing less than a complete explanation of reality - nature, consciousness, art, history, politics, the lot - based on a single self-explanatory idea. Whether or not he succeeded is an interesting question (spoiler: he didn't), but more interesting is the question of why philosophy has become so much less ambitious since then, and what we can learn from Hegel today.