The Do's and Don't's of Agreeable Conversation : Page 195
Similarly when topics are discussed which are beyond your range, you must take particular pains not to hang back or look disinterested. Precisely then is it important for you to attend interestedly, to follow each speaker with your eyes, to learn what can be learned — and to watch for a cue to change the topic to something more congenial.
Once you are talking yourself, even though you got the floor because of someone's kindly question, you will make sure to take in the whole group with your eyes. This is an art which must be learned. A public speaker addressing a thousand must somehow manage continuously to sweep all of them with his eyes. A good talker in a parlor must continually catch the eyes of everyone who is supposed to be listening. Very many people fail to do this. Very often, owing perhaps to a subconscious nervousness, a talker keeps staring at the one who promoted the topic or who sits in the most prominent position or who appears to be most sympathetic. But no matter who raised the subject, or who is host, any remarks that go beyond two sentences must be carried not only to the ears but to the eyes of all present.