It happens nearly every time a new book comes out about motherhood and work -- the flurry of responses that treat reports of a still-unsolved conflict between the two as a revelation, even a shock. Last spring it was "Creating a Life," Sylvia Ann Hewlett's dour statistical inventory of a career gal's chances for procreating. This fall it's Allison Pearson's cannily amusing novel of working-mom manners, "I Don't Know How She Does It." Each book was greeted, as such books almost always are, with professions of deepest surprise, as if it were news that working mothers seldom feel that their lives are in balance, that the competing goods of work and children are just that, competing, and ceaselessly. The perils of "having it all" (a phrase you would think had long since been relegated to 70's nostalgia quizzes) were trotted out again in pursed-lip fashion. Commentators were startled when some maverick finally spoke the truth about a phenomenon -- fertility concerns for older women or the difficulty of operating at full throttle on the job while paying a good deal of attention to your children -- that, in fact, preoccupies many people, who speak about it plenty.

Even the women the press found to interview about these revelations evinced what would seem by now to be a rather naive surprise at the facts of life. Like the fact that in exchange for having both a job that is reasonably fulfilling and children you know reasonably well, there are things you will have to give up, at least for a while (a social life, vaulting ambition, the conviction that a school bake sale is a contest and that you should win it, the belief that a man, however well meaning, will never manage as well on the home front as you will, the whole concept of uninterrupted sleep). Like the fact that fertility declines with age, regardless of how young you look or how dutifully you exercise. Yet "millions of women who are in their 30's and 40's" were "stunned" to find out that it might be too late to become pregnant, Oprah Winfrey announced at the start of the show she dedicated to Hewlett's book. Pearson, whose heroine struggles with a brutish male colleague named Rod Task on the one hand and the judgmental neighborhood "muffia" of stay-at-home moms on the other, was astonished, USA Today reported, when other women wrote to her about their "secret" fears of "failing at work and at home."

Only in the realm of spin is any of this "secret." When you are a working mother, it's true, there is a way in which you never quite get over the radical incommensurability of home and work, never stop marveling about how seamless and seamed your life is at the same time: seamless because after you have had children you can never quite disentangle them from your thoughts about anything in your life, and seamed because so often you have to pretend that you can. And then there is a way in which you get on with it, accept this disparity as the stuff of life, the condition of an existence that you are in fact profoundly lucky to have. You never stop noticing the little collisions of worlds -- the way you may go through a day with spit-up on your don't-mess-with-me black suit or harrowed by a too-vivid memory of your child clinging limpetlike to your leg when you left the house that morning. But after a while, I suspect, most mothers with jobs are no longer surprised that it is hard to combine things that are often at cross-purposes (sick child, work deadline), no longer particularly indignant at the realization that something usually has to give.

So why is it perennial news that "modern women" lead "messy lives," as USA Today put it? (How much better "messy," with all its implications of fullness, than neat.) Maybe because for years the version of feminism that many people absorbed was an advertising promise -- a set of glamorous, fleeting images suggesting insta-liberation. It is shocking, for example, how many references you will find in all kinds of writing about contemporary career women to the ad for Enjoli perfume that ran in the late 70's -- you know, the one with the luscious female exec ("I can bring home the bacon/fry it up in a pan/and never, never, never let you forget you're a man"). Even more than Helen Reddy's "I Am Woman" (which at least contained the hokey but vaguely truthful line "Yes, I've paid the price, but look how much I gained"), it was the anthem of "having it all."

And maybe, too, an earnest, policy-oriented optimism plays a part, since as Marjorie Williams pointed out recently in The Washington Post, Americans tend to hew to the belief that the constant tussle between work and home is a problem that can be solved. "On a personal level, and as a matter of social policy," Williams wrote, "we often seem to be waiting for the No-Fault Fairy to come and explain at last how our deepest conflict can be managed away." For the right, each new book about working mothers' difficulties presents another opportunity to hammer home the point that, really, women with children shouldn't be working outside the home at all. For the left, it's a chance to say that if only there were more subsidized child care or flex-time, we could all go to work with uncluttered hearts. Of course, policy ideas help. Of course, it would be better, much better, to have more part-time work with benefits, more flexible hours, more understanding employers. It would be better, for that matter, to acknowledge that many of the woes limned by writers like Pearson (the scramble for private-school admission, the deep concern about securing the right children's birthday-party entertainer) are the self-imposed trials of affluence, not of womanhood.

But in the end there are limits to what can be fixed, and when it comes to the heart's ambivalence about work and home, maybe that's how it should be. There are certain conflicts that won't be neatly mended, which only means we have to -- we get to -- live with them.