The goal of meditation is to experience stillness. Stillness is the space between thoughts. How is this possible, your might ask? By consciously breathing, focusing solemnly on breathing, you can learn to take a pause in between inhaling and exhaling, and therethrough find stillness. Inhale and count to for example 4, then count and hold your breath for 4, exhale and count to 4 again, and then pause also after the exhale counting to 4. At the end of the round, you can find stillness.
The first time, I experienced stillness, was during an Ashtanga yoga practice in 2002 but I had been meditating weekly since 1995. We were laying on the floor, at the end of our practice, when I found myself being able to observe my thoughts and emotions. I was no longer in the midst of an inner dialogue, but could just breathe, be and listen, letting them come and go.
Once you have found this stillness through presence, you also receive a sense of inner space, from which you can create your next thought and emotion. This is what I refer to as mastery.