At these moments, America has carried on not simply because of the skill or vision of those in high office, but because We the People have remained faithful to the ideals of our forbearers, and true to our founding documents.
[see grammatical analysis here.]
David Rose wrote to sys-func and Sysfling on 18 March 2015 at 09:15, analysing the above clause complex from Barack Obama's Inauguration Speech:
Now from discourse semantics…
‘because’ as preposition or conjunction are alternative realisations of reason (so 2 equal factors)
‘not simply…but’ realises counterexpectancy (not just 1 factor)
 The prepositional phrase realising the circumstance of Cause: reason because of the skill or vision of those in high office and the dependent clause of cause: reason because We the People have remained faithful to the ideals of our forbearers, and true to our founding documents are two grammatical means of construing cause: reason. The insights come from the grammatics, not from a 'discourse semantics'.
 In terms of the metafunctions, 'counterexpectancy' is interpersonal, not logical. That is, 'counterexpectancy' is not a feature of logico-semantic relations, expansion or projection, nor of interdependency (taxis). In the grammar, it is a feature in the system of mood Adjuncts (Halliday & Matthiessen 2004: 128).