2542. 'And spoke all these words in their ears' means an exhortation made to confirmations from this source, even until they should become obedient. This becomes clear from the train of thought in the internal sense, and also from the meaning of 'ears'.

From the train of thought: There are many matters of a confirmatory nature that lend support to whatever the rational acknowledges; indeed its acknowledgement is due entirely to those confirmatory matters. This is why, when rational concepts are brought into a condition of obedience, an exhortation is made to things that confirm, for these are for ever at hand and so to speak rising up.

From the meaning of 'ears': 'Ears' in the internal sense of the Word means obedience because of the correspondence that exists between hearing and obeying. Furthermore, this correspondence lies hidden within the very word 'hearing', more so in 'hearkening'. This correspondence has its origin in the next life where those who are obedient and willing belong to the province of the ear. Indeed they correspond to the faculty of hearing itself, an arcanum unknown as yet. But these matters will be seen more easily when correspondence will be dealt with in the Lord's Divine mercy later on. The fact that 'ears' has this meaning becomes clear from very many places in the Word; but for the time being let only the following in Isaiah be quoted,

Make the heart of this people fat and their ears heavy, and plaster over their eyes, lest they see with their eyes and hear with their ears, and their heart understands. Isaiah 6:10.

Here 'seeing with the eyes' means understanding, and 'hearing with the ears' means perceiving with affection and therefore means obeying. And nothing else is meant when the Lord says,

He who has an ear to hear, let him hear. Matthew 11:15; 13:9, 43; Luke 8:8; 14:35.

Stones in general represent true ideas. Flint is a kind of stone that can be chipped to form extremely sharp edges. To keep the metaphor going we would want flint to be truth that "comes to a point", and in a way that's exactly what it is. According to the Writings, flint represents the "truths of faith" the rules we learn about how to be good people and serve others so that we can apply them as they arise in life. These are relatively black-and-white concepts ("Thou shalt not murder") that help us identify evil desires and arm ourselves against them. This is why flint knives were (and in some cases still are) used for circumcision, which represents purification from our most base love of self and love of the world -- something that must be accomplished by truths of faith.