And what are those two things? First - or second, because they can be reversed - all people would need to KNOW what they think about all that they talk/write about with others. Second - or first, it doesn't really matter - all people would need to actually CLEAR their mind of all that personal noise going between their ears AS they hear/read and consider what others are saying/writing to them. (See how they can be reversed?)
This has been the ongoing problem for most people who've ever lived, even those alive today, even those writing and reading this bit today. Usually the person speaking or writing does not KNOW what they think about all that they talk/write about, and usually those listening or reading have not actually CLEARED their minds of the internal noise of associative language bits and pieces popping up - the agreements, disagreements, approvals, disapprovals, arguments, criticisms, complaints, etc. - which makes communication and understanding between people very difficult at best, and entirely absent at worst.
Unfortunately, neither of these skills, or capacities, or talents - who knows what to call them? - can even be taught. EITHER, you know how to KNOW what you think about what you talk and write about, or you don't. EITHER, you can CLEAR your mind of all the associative noise-making going on in there as you listen to or read others' offerings, or you don't. The only "teaching" that can be offered, really, is contained in the expressed observation that people generally do NOT know what they think about things, and they also can NOT clear their minds when listening to and reading others' offerings. THAT observation should really be enough for most sane and reasonably well educated people (either by Life itself, or from books - it doesn't matter so much), but what usually happens, is just more of the same knee-jerk reactions to whatever is presented, rather than full and complete reception of all that was offered.
The Big Two are here to stay, I'm sorry to say, though that is certainly not the end of it for those few who have "progressed" beyond the situation outlined above. For those few, a new level of communication can proceed, both internally, as one thinks about and considers new and interesting ideas, and externally, as they attempt to share them with others and hear and understand what others are saying. But, just consider for a few moments how these two things would have changed EVERYTHING for humans. One person could "advise" another person about something, and they would understand that "advice" and perhaps even be able to use it. One person could "instruct" another, and they would Get It, and perhaps be able to quickly use it. Instead, what do we always see, everywhere? People arguing, fighting, and going round and round the same point in the ground year after year, and in the end be worse off than they were before.
Check it out.