You are under an impression,. This makes you say “I am under a particular impression. And
it seems
this sentence seems
to say to yourself under what impression you are ˇat least that you have told yourself under what impr. you are.
   As though you had pointed to a picture ready in your mind & said this is it.
    Whereas you have only pointed to your impression.
   You did something like drawing a circle round the colour …