The granular ubiquity of "referent and reference" -

Every bit of thought that you wish to express in language has a "subject" and a "predicate", (of a certain sort, defined below).

Consider this sentence - John gave a ball to Jack.

This information has 3 "parts" - 1. John gave (that John gave) 2. a ball (that a ball was given) 3. to Jack (that the ball was given to Jack).

Now take, say, the 3rd part - 'to Jack'. That's a small piece of knowledge within the broader whole knowledge (John gave a ball to Jack), that the ball was given 'to Jack'. Now consider just 'to Jack'. In conveying that the recipient of the ball was Jack (which 'to Jack' does) the expression in language is such that things are talked using Jack as a reference, and saying 'to' about him, implying that the recipient was someone (Jack). So the 'Jack' is the subject (with reference to which things are talked) and the 'to' is the predicate which is what is talked with reference to what is referred to.

One can see similarly, for parts 1 and 2 -

1. Subject - John. Predicate - gave.

2. Subject - ball. Predicate - A.

In every microscopic piece of knowledge too, there is something with reference to which that you talk, and there is the talk.