Sentence:  As retinal images are conceded to be an integral function of the brain it seems logical to suppose that the nerves , between the inner brain and the eyes , carry the direct drive for cooperation from the various brain centers - rather than to <WSD>theorize</WSD> on the transmission of an image which is already in required location . 
Meaning of the word marked with <WSD> tags:  to believe especially on uncertain or tentative grounds