There are two kinds of men in the operating room -- those who are spooked and those who aren't. Ian McEwan has discovered that he belongs firmly in the latter camp.

		Related coverage Book Review: 'Saturday,' by Ian McEwan

A year ago, the 56-year-old Booker-winning novelist began a new book, and as part of his research he accompanied a neurologist to brain surgery.

"I didn't know what my level of squeamishness was," says McEwan.

"But as it turned out, I just had total fascination. From the very first use of the skin knife to part the scalp, it was just amazing. I couldn't wait until [the doctor] cut through the dura and got to the brain itself."

Although McEwan claims this lack of disgust came as a surprise to him, readers familiar with his earlier nickname -- Ian Macabre -- might find this hard to believe.

After all, this is the same writer who wrote "Solid Geometry," a story about a man who kept a pickled penis on his desk.

In the past three decades, though, McEwan has come a long way from these ghoulish early works, graduating to robust meditations on family ("A Child in Time" and "Black Dogs"), betrayal ("Amsterdam") and the metaphysical bargains of the writing life ("Atonement").

If you want to judge just how far McEwan has come from his early roots, though, pick up his new novel, "Saturday," which follows a day in the life of neurologist Henry Perowne. With deceptive boldness, the novel writes itself "right into the present tense," as McEwan says, referring to how the book references the war in Iraq.

In the process, it chronicles a man's thoughts more closely than McEwan has done before.

His hero heads forth on a Saturday much as Clarissa Dalloway does on her perambulation through London in Virginia Woolf's novel.

"I wanted to sort of do pleasure," says Mc Ewan. "But I also wanted to describe in detail the mental processes by which our pleasure is interwoven with our anxiety.

"As we sit here worried about the state of the world, we're certainly not about to do anything about it."

For many people in the Western world, anxiety runs "like a fugue with our pleasures," says McEwan, neither one upsetting or overwhelming its counterpart.

"Saturday" further twists the knife, though, by pitching Perowne into two interactions which give him a similar sense of futility as international disasters.

One is his run-in with a violent man whose Huntington's disease he can diagnose but not control.

The other is a visit to his mother, who, as McEwan's mother once did, suffers from vascular dementia, a condition that has robbed her of her memory.

"I wanted to capture what it's like to sit with your mother and have her not recognize you," McEwan says. "You can have all the descriptions of disintegrated neural nets, deficiencies, but that doesn't relieve you of the tragedy of her mind closing down."

In this regard, "Saturday" feels as if it might be the first of a coming wave of novels that address the sense of apprehension that came in the wake of Sept. 11, how it lingers and interacts with the day-to-day worries of our lives.

Like many other novelists, McEwan was not expecting to go in this direction. In 2001, he was set to write a comic novel, but then the 9/11 attacks occurred.

"I didn't think about writing at all: I watched news programs, read newspapers, read books about Islam. Like everyone else, I suppose."

When he emerged from this period, McEwan decided he had to engage the present.

"I was thinking then, well, now that there was clearly going to be an invasion of Iraq, I'll let history take the course of the novel. Then I thought that would be too complex. I needed structure, so I based it around a single day."

Although more contemporary, "Saturday" has a significant relationship with "Atonement," the sprawling 2001 novel about a child's lie that destroys a man's life and makes her a writer in the process.

"Saturday" is the adult counterpoint to "Atonement," providing a more mature look at the question of consciousness and writing.

McEwan has set out to atomize a man's empathic response to the world based not on religion or art, but on matter.

"I've always thought that there was a sort of kidnapping," says McEwan with a wry grin, "that the major world religions have tried to persuade us that they're God's gift to morality, and that forgiveness can only come from religion. I wanted to show that Perowne could arrive at a similar kind of forgiveness from entirely different means. That to believe that consciousness proceeds from matter can give you an infinitely rich hold on life, a quite celebratory one."