and Water

At the bottom of page eighteen and continuing onto PAGE NINETEEN, it's four-element meditation of earth, wind, fire and water.  It's recommended here to focus in the elements within the body due to its closeness to the person practicing.  Sayadaw asserts that following increased awareness of the elements of the body, one must discern also past, future, present, external, gross, subtle, inferior, superior, far and near.  They appear to be relational and from the Khanda Sutta:

"Whatever form is past, future, or present; internal or external; blatant or subtle; common or sublime; far or near: That is called the form aggregate.
"Whatever feeling is past, future, or present; internal or external; blatant or subtle; common or sublime; far or near: That is called the feeling aggregate.

"Whatever perception is past, future, or present; internal or external; blatant or subtle; common or sublime; far or near: That is called the perception aggregate.
"Whatever (mental) fabrications are past, future, or present; internal or external; blatant or subtle; common or sublime; far or near: Those are called the fabrications aggregate.
"Whatever consciousness is past, future, or present; internal or external; blatant or subtle; common or sublime; far or near: That is called the consciousness aggregate.

Scanning ahead, there are many more beginning pages before Sayadaw describes meditation upon these elements.  I don't know how perception or felling can be 'far' or even really 'external'.  But I'll wait here and observe and see what coheres, or falls away.