The expression “we eat with our eyes (first)” means that we see food before we eat it, so food preparation should also include making the food appear attractive. The Chinese poet and gastronome Yuan Mei (1716-1797) gave the advice:
 
“Another maxim is, ‘Don’t eat with your eyes.’ This is a warning to hosts against providing too many courses.”
 
“We do eat with our eyes” was cited in the American magazine The Horticulturist in 1864. “We eat with our eyes as well as our palate” is an uncredited proverb that appeared in several newspapers in 1900.
 
   
Wikipedia: Yuan Mei
Yuan Mei (袁枚 pinyin: Yuán Méi, 1716–1797) was a well-known poet, scholar, artist, and gastronome of the Qing Dynasty.
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Yuan as a gastronome
The food writer Fuchsia Dunlop has described Yuan as “China’s Brillat-Savarin,” and is called one of the four classical gastronomes. In a time when the taste among his contemporaries was for opulence and exotic display, Yuan stood for the “orthodox” style. “Nowadays,” he wrote, “at the start of the feast the menu is about a hundred feet long.” This is “mere display, not gastronomy.” After such a dinner Yuan returned home and cooked congee to appease his hunger. He instructed cooks “do not fuss with the natural state of the food just to show that you are a clever cook. Bird’s nest is beautiful—why shape it into balls?” Yuan criticized his contemporary Li Liweng’s magnolia pudding as “created by artifice.” Yuan also resented what he regarded as the corruption of Chinese food by Manchu cooks. The appeal of Manchu cooking was in their stews and roasts, while Chinese cooked broths and soups, but when Manchus serve Chinese dinners and Chinese serve Manchu food, “we lose our originality” and we “toady to each other.” He published his collection of recipes in his Suiyuan Shidan (Cookery Book).
 
Hathi Trust
October 1864, The Horticulturist, pg. 321, col. 1:
This is both a table and wine grape, with thin skin and melting pulp under the pressure of the tongue, while all agreed on its early ripening, hardiness and fine flavor, some fears were expressed that it would not be a good market grap as the berries were loose on the bunch, to which one gentleman replied that “we do eat with our eyes.”
   
Hathi Trust
10 December 1874, The Cultivator & Country Gentleman, “Making Butter in Winter,” pg. 791, col. 3:
It may not add to its flavor, but it certainly does to its appearance, and we eat with our eyes as well as with our teeth.
 
21 October 1885, Boston (MA) Herald, “Dinner Giving: Advice from China as to the Art of Entertaining,” pg. 5, col. 2:
Another maxim is, “Don’t eat with your eyes.” This is a warning to hosts against providing too many courses.
   
6 June 1900, The Evening News (Saginaw, MI), pg. 2, col. 2: 
We eat with our eyes as well as our palate.
 
23 November 1900, New York (NY) Times, pg. 4 ad:
Every tasteful and ambitious housekeeper is already planning for the Thanksgiving Dinner; and somebody has said: “We eat with our eyes as well as our palate;” so the table should look as pretty as the dinner tastes good.
(The Wanamaker Store—ed.)
 
Google Books
A History of Chinese Literature
By Herbert Allen Giles
London: Heinemann
1901
Pg. 411:
”Don’t eat with your eyes; by which I mean do not cover the table with innumerable dishes and multiply courses indefinitely. For this is to eat with the eyes, and not with the mouth.”
 
Hathi Trust
Canning and Preserving Food Products with Bacteriological Technique
By Edward Wiley Duckwall
Pittsburgh, PA: Pittsburgh Printing Company
1905
Pg. 303:
In a sense we all eat with our eyes, and it is a question whether food has the same value if it does not appeal to the eye. Several experiments have been tried upon animals by feeding them blindfold and the results gave evidence that the food did not accomplish its full value, for the animals grew weak and emaciated.
 
13 June 1905, Philadelphia (PA) Inquirer, pg. 7, col. 6 ad:
...you remember the old adage—“We eat with our eyes as well as our palate.”
(Strawbridge & Clothier—ed.)
 
14 May 1927, Denton (MD) Journal, “Food Flavor and Color in Golden Enamel Cans,” pg. 2, col. 5:
Doubtless another reason forthe increasing popularity ofthe new can is the aesthetic sensibilities of the woman in the home—which is another way of saying: “We eat first with our eyes.”
   
Hathi Trust
The Art of Cooking and Serving
By Sarah Field Splint
Cincinnati, OH: Procter & Gamble
1930
Pg. 138:
Be particular about the appearance of your salad. Remember many of us “eat with our eyes.”
 
28 January 1933, The Times-Picayune (New Orleans, LA), “Sick Room Diet Needs Some Care” by Estelle Marie Barker, pg. 17, col. 1:
The first point is attractive and varied service. We eat with our eyes first, you know, and even the prettiest china pall upon us if they come too frequently without change.
 
Google Books
Hospital Management
Volume 72
1951
Pg. 110:
Since we first “eat with our eyes” garnishes are as important to food as accessories are to clothes.
   
Google News Archive
13 January 1966, Owosso (MI) Argus-Press, “The Market Basket” by Eileen Bell, pg. 29, col. 2:
We eat with our eyes first, don’t we? So most Florida oranges are degreened by a shot of ethylene gas and then get dunked into a coloring tank.
 
Google Books
Elements of Food Production and Baking
By Aaron Kaplan
New York, NY: ITT Educational Services
1971
Pg. 40:
Texture, Flavor, and Appearance
Cover food to provide a pleasing texture, color, and appearance. We eat with our eyes first and have become accustomed visually to a variety of foods with defined characteristics which we either like or dislike.
 
OCLC WorldCat record
You eat with your eyes : the simplicity & elegance of presenting food
Author: Edward G Leonard
Publisher: United States : LTD Publishing, ©2008.
Edition/Format:  Book : English
 
Google Books
Nursing Assistant:
A nursing process approach
By Barbara R, Hegner, Barbara Acello and Esther Caldwell
Clifton Park, NY: Delmar/Cengage Learning
2010
Pg. 575:
You may have heard the expression, “You eat with your eyes.” This means that you are much more likely to select food that is attractive in appearance, because it looks good to you.
 
Google Books
The Skinnygirl Dish:
Easy Recipes for Your Naturally Thin Life
By Bethenny Frankel
New York, NY: Simon & Schuster
2010
Pg. 44:
You eat with your eyes first, so how food looks really does matter. This is where it’s worth taking extra time to make your food really special. Think about the food you would get at a spa or at a nice restaurant.
 
New Zealand Herald
The dish: Let it sow
By Nici Wickes
(...)
How often have you heard the expression “presentation is everything, we eat with our eyes first”? Well, for three nights (November 13, 14 and 20), Euro will be tossing this theory aside and offering a blind tasting menu - literally.
5:00 AM Wednesday Nov 2, 2011