Greetings..
As others have mentioned, the mind filters all of our input.. one of the primary benefits of meditation, as is my experience, is that we can minimize the filtering process and have a more clear (clarity) experience of the world we live in.. this is a great assist in formulating opinions of our experiences.. too often our prejudices and preferences influence our perception of the experiences we have to the point that we really don't have a pure experience, we have a projection of our prejudices on the experience.. my goal, and i hope the goal of others, is to try to have direct experiences, as unprejudiced as possible.. to see the world clearly.. So, when someone says "still the mind", the concept is to suspend the thought processes and let the current experience impact us directly.. as we think about the previous experience the current experience slips by almost unnoticed (lost in thought).. to the degree that it is possible, i try to quiet the mental chatter we call thinking (although for me it's more like a committee debate.. all those voices...)..
Be well..
TaiChiBob.. "the teacher that is not also a student is neither"