Whitehead, Lonergan and relations

In the concluding chapter of his little book, What are they saying about Dogma (New York: Paulist, 1978), William E. Reiser, SJ, suddenly appeals to Whitehead's process philosophy. He informs us that the key concept in Aristotelian philosophy was substance; Whitehead would substitute that with relation. Then, a very revealing sentence:

When one thing changes, everything else is somehow affected, however minimally. (58)

If reality is a texture of pure relations, then we probably have a situation like that of Hegel, where there is no place for the truly contingent. See Lonergan, Insight, ch. 11, section 11:

Now, if one supposes that the whole universe is a pattern of internal relations, clearly it follows that no part and no aspect of the universe can be known in isolation from any other part or aspect; for every item is related internally to every other; and to prescind from such relations is to prescind from things as they are and to substitute in their plae other, imaginary objects that simply are not.... (CWL 3:367) 

This section must be read in conjunction with ch. 16, section 2, where relations are conceived of as having two components, primary and secondary, which distinction serves to separate the systematic and the nonsystematic. (CWL 3:515) Despite the fact that the shift from description to explanation involves a shift from external to internal relations, in a fully explanatory account of the universe external relations also survive. (CWL 3:518)

These are deep waters; but no doubt they have to be traversed if we are to get to the bottom of the matter.