Here are a few possible interpretations:
1. Lying: This is the most straightforward interpretation. The phrase could mean telling lies, pretending that things are true when they are not.
2. Imagining: This could also refer to imaginative storytelling or creating fictional worlds. You might "speak things that be not" by writing a story or creating a character that doesn't exist in reality.
3. Hypothetical Reasoning: This could refer to discussing possibilities or hypotheticals. For example, "What if we could fly?" You are "speaking things that be not" in the sense that you're talking about something that doesn't currently exist.
4. Metaphor and Symbolism: The phrase could also refer to using figurative language like metaphors or symbols to represent abstract ideas. You might "speak things that be not" by using a metaphor to describe an emotion or feeling.
Ultimately, the meaning of the phrase depends on the context in which it's used. It's a provocative statement that invites us to consider the relationship between language, reality, and imagination.