We washed the oysters in the lagoon, and then opened them with our jack-knives and ate them raw. This took some nerve on my part, since it was my understanding that not only were they raw, but actually alive as well

My companion went first, taking one onto his tongue. When he swallowed, he motioned toward me. "Wait a few minutes -- to see if there's any adverse reaction."

In the end I did partake, but had fewer than the Marine, who seemed really to like them. I based my meal more on the fruit. To make this more palatable, I had gone to my palm taps and emptied the contents of both into the water bag -- letting it mix with the water that was left.

When I opened the bag during the dinner, however, I was taken aback.

"It's gone off," I said, sniffing the opening.

My companion took it and sniffed as well.

"It smell a little -- like alcohol." He took a sip. "Tastes like it as well."

"I guess the sugar in the sap fermented," I said. "I wonder if it's still okay to drink."

The Marine nodded, and took another, longer sip from the bag. "I'll let you know."

When he had had almost half of the bag's contents, I asked if I could have the bag. Grinning, he handed it over -- with a show of reluctance.

"I feel," he murmured, "slightly -- good."

I drank some of the mixture, and tasted the alcohol. After a minute or too, I began to feel good as well.

We shared the remainder, and both agreeing that there was some amount of inebriation.

"Or maybe it's the oysters," the Marine said.

"What it are you referring to?" I asked.

He frowned at me. "That I feel good." He considered and then murmured. "Real good."

I suppressed a wide grin. "Oh, yeah," I said, feigning simple curiosity. "Good -- how?"

The Marine, catching my tone, stared at me.

Deciding to continue my pulling of his leg, I smiled innocently and shrugged.

"Well," I said, not looking at him, "you know that oysters have long been considered aphrodisiacs -- you know, increasing the sex drive. There are stories of famous lovers eating them before going out on the prowl."

"Considered," the Marine repeated. "But is it true? Is there any evidence that they have an effect?"

I hesitated, then nodded. "Of course."

I was not actually lying. The evidence I was referring to was the effect of believing that oysters were aphrodisiacs. One of the most consistent findings of psychological studies is that there is on average a 20% placebo effect in any trial -- that is, when a non-active substance has, unknowing to the subject, replaced the active ingredient. It is the subject's belief in the expected effect while taking only the non-existent drug that actually causes the effect. I stated it like this, to see my companion's reaction.

I wasn't disappointed.

The Marine sat upright and looked down at his crotch.

"You're kidding!" he murmured, feeling himself.

I was just telling myself that I should explain the truth in my statement, to reassure him. But I'm afraid at this point I became interested in the effect his belief was having, and more or less forgot about the explanation entirely.

Basically, I just wanted to see what would happen next.

The answer was -- at least in the short-term -- nothing much, except that the Marine continued to appear slightly disturbed or preoccupied.

As I watched him, I questioned my own motives. It wasn't amusement I felt, but rather, a kind of wonder and admiration -- and respect. I was watching how a trained Marine, a man of "honor, courage and commitment" -- as their stated values maintain, was dealing with an inner perception, real or imagined (there actually is no difference -- in psychology everything is at bottom mental), something that he found disturbing.

As the saying goes, it is not the challenges we face, but how we respond to them that shows what we are made of.

I was impressed. Clearly there was some sort of inner battle, some consternation within the man. Yet he was keeping his outward cool, though he did avoid my gaze.

"You okay?" I said at last.

He nodded, still not looking at me.