Did he think it was the actual spirit of his father or a hallucination his mind built and then used all memories to extrapolate what kind of advice his father would give? I was never clear on this.
From what I understand, the device was supposed to imitate the effects of herbs such as Peyote, etc to enlighten you and guide you without making you...high.
So it was probably NOT his father. Just some sort of hallucination. But I also am not clear on this.