If a boat is left by itself on the ocean, it will be in constant motion: moving this way with the tides, that way with the wind, another way with a current. The boat itself has no say in where it goes, helpless before the forces of sea, sky and moon.
Our mind is that boat. The wind is our thoughts, the tides our emotions and the currents, our desires and the overwhelming distractions of the world. Left by itself, our mind cannot stay still, being constantly pulled, pushed and lured this way and that – and mindlessly following.
The first prerequisite of meditation is to calm, and ultimately to still, the mind.
To fix a boat in one place, requires an anchor or mooring. Similarly, to fix our mind so that it is not swept away by distractions, thoughts and desires, requires a mind-anchor, a firm object of concentration.
This “anchor” can be a physical object to look at such as a candle flame or flower; it might be a sound such as music or a mantra; a mental process like counting; the inflow and outflow of our breath; or a scene created in our mind’s eye.
Most “meditation exercises” are simply exercises in concentration; the process of focusing and anchoring our mind on one thought, one object, one sound, one feeling to the exclusion of all else. Of course the mind will still wander, for that is its nature. Without an anchor, it will drift all over the sea: with an anchor, it will only be able to go so far before it is brought back to a point of stillness.
By virtue of daily practise, the mind gradually becomes used to remaining in the one place. In the mind’s stillness, meditation may commence.