Understanding.
That which is accessible; that which is within one's reach or ability.
Grip.
To take advantage of something, to seize, to jump at a chance.
To grip; to take hold, particularly with the hand.
To understand.
Sanity.
Bits of rolled-up rubber shed by the tires of race cars that accumulate at the edges of the track, especially at the corners.
Any of several children's games played with small balls (made of marble or more commonly glass).