Full Idea
'Graspng' a structure would seem to bring into play something like a modal sense or ability, not just to register how things are, but also to anticipate how certain elements of the system would behave.
Gist of Idea
'Grasping' a structure seems to be modal, because we must anticipate its behaviour
Source
Stephen R. Grimm (Understanding [2011], 2)
Book Reference
'Routledge Companion to Epistemology', ed/tr. Bernecker,S/Pritchard,D [Routledge 2014], p.89
A Reaction
In the case of the chronology of some historical events, talking of 'grasping' or 'understanding' seems wrong because the facts are static and invariant. That seems to support the present idea. But you might 'understand' a pattern if you can reproduce it.