Lyric discussion by DarkerShadeofWinter 

Cover art for Silas' Knife lyrics by Appleseed Cast, The

In the conceptual story of Peregrine, I believe this song is a narrative from the daughter, Peregrine, to her brother fighting his enmity and reclusion (whose name seems to be Silas.) This all seems to be a result of the miscreant in this story: the formerly loving and affectionate, now turned conniving and diabolical, "Father."

As far as I can guess, judging by the knife and nature motifs, Silas' (more bitter than sweet) nostalgic memories are most likely traumatized by the realization of horrors he experienced while hunting. This is most likely introduced, but not touched upon, in "Woodland Hunter (Part I)" and continue on throughout this song and a few other times on the album. Peregrine realizes and understands her brothers pain, and wants him to face reality and face himself, the world and his father. She begs him to persevere; to abstain himself from the family horror and trauma caused by her father's actions. She wants him to stand up for himself, for he cannot be defeated.

Whether or not the 'cave' is real or metaphorical I cannot decipher, but if it is real it would imply that he's quite literally living in the wilderness and hunting for survival; something I think would be quite interesting and depictive of primal instinct and maybe even heavy psychosis. If it isn't an actual cave, I think it might refer to either the mental 'cave,' or rut, so to speak, or perhaps even a really nasty, maybe even dilapidated apartment-- think Taxi Driver here, folks.