Communing with deity via divination tools can be quite an extensive learning.
Like Hearth said, you will want first to elimimanate phtsical or natural causes for the candle to flicker.
I recently had a short capnomancy session with deity, tonight rather, I was in an incense lighting mood.
I you see was asking the deity for confirmation of her role in my path work. Asking if she will indeed help in certain areas. Much of my reading was affirmative and I threw in a few quite irrelevant no questions for testing of accuracy. You see the incense smoke is supposed to change direction depending on the answer.
Which again brings us to testing. Like hearth said, see if the same exact candle brand, color and type does the same.
What cemented my reading as a positive sign of a deity communication for me, was I looked over at my lamp and within my visionary feild for what was only a moment, was a brown feathered wing.
The deity I work with is often depicted with wings. This image also confirmed what I had asked.
Be aware with this. Take your time when working with communicating with deity via divinatory means and tools. And practice, a lot.
If you wish to know what a candle flicker means by flame reading, it is often generally written to mean that a spirit is present.
But you'll want to test some things first.
Blessings.
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