Epistemological reach is the primary factor of ontological extent. As understanding grows, so does depth, intensity, efficacy, and causal influence of being. Growth of understanding is increase of substance; “substans” is the Latin for “understand” (and “hypostasis” the Greek).
To understand a phenomenon is to relate its particular form to more general principles.
The infant cannot at first relate any of the phenomena of his sensorium to any others, but as he grows their categories and principles become more and more apparent to him, until he is able to form a mental model of reality. Then he can sort new experiences into his model – or, failing thereat, struggle to improve the adequacy of his model. As his understanding grows, he is affected less and less by this or that immediate sensation, and more and more by considerations of a more general nature. He stands under the guidance of an ever more capacious and expansive system of principles, that more and more transcend the moment to moment vicissitudes of his life, and provide him the patience and solace – the courage – that he needs in time of hunger or thirst or danger, the confidence that he will soon find relief from his discomforts. He more and more guides his life according to principles of a greater and greater generality.
Eventually, as he grows, he recognizes that God is the most fundamental principle, the principal of all principles. He realizes that the order and regularity he has already apprehended in the world have their origin in God. He realizes that if he can understand God, and walk in the ways that are good, true and beautiful under God, then everything else – all subsidiary principles, and all their instantiations and operations – must fall into their proper order. He realizes with Socrates that to understand is to depart from evil (Job 28:28). At this realization, the quest for sagacity, for sainthood – for fullness of being, theosis – begins.
TEACH me, O LORD, the way of thy statutes, * and I shall keep it unto the end.
Give me understanding, and I shall keep thy law; * yea, I shall keep it with my whole heart.
Make me to go in the path of thy commandments; * for therein is my desire.
Incline mine heart unto thy testimonies, * and not to covetousness.
O turn away mine eyes, lest they behold vanity; * and quicken thou me in thy way.
O stablish thy word in thy servant, * that I may fear thee.
Take away the rebuke that I am afraid of; * for thy judgments are good.
Behold, my delight is in thy commandments; * O quicken me in thy righteousness.
— Psalm 119:33-40