Here is his take on this subject:
“Every fancier has his own traditions, his own certainties and his own clues, which he tries to recognise when holding a real champion in the hand. Still we all have to agree that our theories and ideas do not match reality very often. Most of us have to admit that some fanciers have a better feeling than the average fancier, even though there are no visible or noticeable differences between a true champion and a less successful pigeon. As a result an increasing number of fanciers have been looking for all sorts of theories and ideas to actually recognise the quality of a pigeon. Besides some of the most ridiculous theories we are also familiar with the three big theories: the eye, wing and muscle theory. A fancier who adds value to either of these theories is bound to make mistakes.
The eye theory
You can read more about the eye theory by clicking here. (in Dutch)
Great books have been written about this theory and every inexperienced fancier tries to discover things in the eye of a pigeon. I think a veterinary surgeon would be highly amused to hear a big champion say that you should never pair two white eyed pigeons. Why would there be a difference between blue, white or green eyes? Sometimes the most wonderful eyes cannot see more than 10 metres (think for instance of short sighted people). On the other hand we can assume that a smart pigeon sees differently compared to less intelligent pigeons and that the smart pigeon has no fear.