Full Idea
That human perception is always a 'seeing as' was the cardinal insight of what Husserl called 'phenomenology'.
Gist of Idea
In phenomenology, all perception is 'seeing as'
Source
Jens Zimmermann (Hermeneutics: a very short introduction [2015], 2 'Husserl's')
A Reaction
I presume that 'cardinal insight' means there is no possibility of Husserl being wrong about this. What's happening before you figure out what it is you are looking at?
Book Reference
Zimmerman,Jens: 'Hermeneutics: very short introduction' [OUP 2015], p.33