Its imprisoned fire must be awakened by the sharp strokes of steel, or no true light of life can arise in itWilliam Law
An Appeal to All that Doubt (William Law)
Law is not talking about a fire you have to build. He says it is already in you, bound and shut up, and that no amount of thinking will set it alight. Something has to strike it. He does not say what will strike yours. He says only that until something does, the light stays where it is.
From the Library: An Appeal to All that Doubt, William Law