("Don't get excited. You got your sleep and I built up my vocabulary. You're fully rested, so what's your complaint? By the way, I can now tell you how I entered your head. I seeped into your pores and then into your scalp capillaries, which I followed into your parietal emissary veins. These flow through the parietal foramina in your skull and empty into the superior sagittal sinus. From there it was easy to infiltrate your central nervous system.")

Dalt opened his mouth to say that he really didn't care, when he realized that he understood exactly what the voice was saying. He had a clear picture of the described path floating through his mind.

"How come I know what you're talking about? I seem to understand but I don't remember ever hearing those terms before ... and then again, I do. It's weird."

("It must seem rather odd,") the voice concurred. ("What has happened is that I've made my new knowledge available to you. The result is you experience the fruits of the learning process without having gone through it. You know facts without remembering having learned them.")

"Well," Dalt said, rising to his feet, "at least you're not a complete parasite."

("I resent that! We're partners ... a symbiosis!")

"I suppose you may come in handy now and then." Dalt sighed.

("I already have.")

"What's that supposed to mean?"

("I found a small neoplasm in your lung—middle lobe on the right. It might well have become malignant.")

"Then let's get back to the doc before it metastatizes!" Dalt said, and idly realized that a few hours ago he would have been worrying about "spread" rather than "metastasis."

("There's no need to worry, Steve. I killed it off.")

"How'd you do that?"

("I just worked through your vascular system and selectively cut off the blood supply to that particular group of cells."