In al-Haytham's Opticae Thesaurus, the following sentence (discussing what the first book will describe) confuses me:
Primum est quod lux per se et colores illuminati operentur in visum aliquam operationem.
It seems to say (fairly literal transl.) "First is that light by itself and illuminated colors work within the eyes some operation." My confusion is with the use of accusative 'aliquam operationem' which I'm guessing goes with 'operentur', but that doesn't seem to work; and the use of 'in (+acc)' which I understand as 'into' typically, but here I read it more like 'within'. Generally I'm having a hard time reading the sentence correctly, is the syntax unusual? Or is it related to the subjunctive 'operentur'?