In any given period, an unspoken underlying structure (the episteme) defines what can count as valid knowledge and what relations between things are thinkable at all. It operates beneath the conscious theories of individual thinkers, setting the conditions of possibility for their claims rather than being chosen by them.
The transition between epistemes (Renaissance to Classical to modern) happens through abrupt discontinuities, not through gradual progress toward truth. Whole systems of thought reorganize at once, so apparent advances are reshufflings of what is sayable rather than steps closer to a fixed reality.
In the Renaissance episteme, knowing meant tracing similitudes: things were linked by convenience, emulation, analogy, and sympathy, and words were treated as signatures stamped onto the world. Interpretation was endless because every resemblance pointed to another, with language and things sharing one continuous fabric.
In the Classical age, knowledge became a matter of representation: of laying out identities and differences in a table and ordering things through analysis and taxonomy. Language detached from things to become a transparent instrument that names and classifies, replacing resemblance with measurement and order.
The figure of 'man' as both the object of study and the knowing subject did not exist as a stable category before the end of the eighteenth century; it emerged only when the modern episteme made human finitude the ground of knowledge. This makes man a historical construct of a particular arrangement, not a timeless given.
Because 'man' appeared as an effect of a specific episteme, that figure could dissolve if the underlying arrangement of knowledge shifts again, like a face drawn in sand erased by the sea. The human sciences therefore stand on a recent and potentially transient foundation rather than a permanent one.