Arcana Coelestia #3152
3152. 'And he said, Speak on!' means desire for it. This is clear from the meaning of 'speaking words' as giving instruction, here of 'Speak on!' as a command to give instruction. That these words imply the desire for it is self-evident.
Speak
Like "say," the word "speak" refers to thoughts and feelings moving from our more internal spiritual levels to our more external ones -- and ultimately from the Lord, who is in a sense the most internal spiritual level of all. This is generally called "influx" and "perception" in the Writings, meaning they are thoughts and feelings that flow in in a complete way from the Lord, rather than being things we have to think about and figure out. On a number of occasions "speak" and "say" are used together; in these cases "speak" refers more to intellectual instruction in matters of thought and "say" refers more to feelings and affections that flow in directly.