Knowing about levels is a kind of key to unlocking the causes of things and probing into them. In the absence of this knowledge, hardly anything can be known about causes. In the absence of this knowledge, the objects and subjects of both worlds look so simple that there seems to be nothing within them beyond what meets the eye. Actually, though, in comparison to what lies hidden within, this surface is like one feature compared to a thousand or ten thousand.
There is no way to uncover these deeper, invisible features without a knowledge of levels. We move from outer to inner and then to inmost by levels, and not by gradual levels but by distinct ones. “Gradual levels”is the name we give to declines or decreases from coarser to finer or denser to rarer, or better, to gains or increases from finer to coarser or from rarer to denser. They are just like going from light to darkness or from warmth to cold.
In contrast, distinct levels are totally different. They are like antecedent, subsequent, and final events, or like the purpose, the means, and the result. We refer to them as “distinct”because the antecedent event exists in its own right, the subsequent event in its own right, and the final event in its own right; and yet taken together they constitute a single whole.
Our atmospheres from top to bottom, from sun to earth, the atmospheres called ethers and airs, are marked off in levels of this kind. They are like the elements, compounds, and compounds of compounds that, taken all together, constitute a complex entity. These levels are distinct because they arise separately. They are what we mean by “vertical levels.”The other levels, though, are gradual because they increase evenly. These are what we mean by “horizontal levels.”
from Divine Love and Wisdom, Section 184