"I knew there was an old axe down cellar; that is all I knew"

In this quote, Lizzie Andrew Borden is reviewing her knowledge of a specific object in her home - an old axe that is kept in the cellar. Making use of the word "knew" suggests that this is not brand-new information to her, but rather something she has actually understood for a long time. The fact that she specifies the area of the axe - "down cellar" - includes a sense of secrecy or hiddenness to the object. This quote might also be interpreted as foreshadowing, as the axe eventually becomes a key piece of proof in the notorious murder case including Lizzie's dad and stepmother.