The eyes must see all sides reveals the issues one has with the mindset. Mindset is an aspect to both life and martial arts that drives us toward success. It is ours and our responsibility that has no tolerance toward projecting blame on others and other things, it is our responsibility. The eyes must have the ability to see the mindset issues and problems so as to reveal the errors humans make due to perceived expertise or mastery.
Mastery, if not seen within the mindset of the master blinds the person to seeing things beyond what they perceive as mastery. It hinders our perception of the cues and options, to ignore potentially useful strategies, and to fail at noticing opportunities that arise in each moment.
Allowing a mastery or expertise to exist means we assume that there is nothing more to learn, to study or to practice. It stunts the growth of our intuitive-analytical ability especially in stressful and dangerous situations. To block or hinder our intuitive mindset process is to set it to a dogmatic immobile perception of the world so that one can not see it any other way.
When you think of those systems that remain dogmatically glued to a practice and training that is born of some master long ago without the crucial requirement to extend that practice and training beyond the mere fundamentals taught as the origins of the system then you fail to see the true potential and growth of that system. It is honorable to desire that one's practice of a system similar or exact to what they were taught by the master and originator but to remain steadfast and doggedly attached to it stifling the growth of it are just wrong. The ken-po goku-i teaches us that this is not conducive to the growth of any system, i.e. the shu-ha-ri of martial systems.
The eyes must see all sides goes way beyond the sense if sight. Seeing goes way beyond merely seeing. It is an intuitive analytical means of truly and without bias seeing the world and all it contains so that perceptions are true to the individual and thus to the whole of humanity.