Naomi Stadlen likes mothers. She has written two books with the word in the title: What Mothers Do, Especially When it Looks Like Nothing and her latest one, How Mothers Love and How Relationships are Born. She has for 20 years run weekly Mothers Talking meetings, at which she chats with mothers about the sort of week they have had, spring-boarding various discussions. She is a mother of three and a grandmother of two. I don’t think to ask how old she is as it doesn’t seem to matter; she is in the “wise” category. She’s an existential psychotherapist, so I know she is careful with words because she understands the weight they carry. Her answer to the question “Why are you obsessed with mothers?” is unexpected. “I come from a line of problematic mothers.” Oh.

These include a grandmother who seemed to have used up her mothering energy on her siblings and “used to spend a lot of time asleep on the sofa”, largely bored by her own two children and rather neglecting them; a great-grandmother who had eight children, three of whom were said to be acutely unhappy; and a mother who was told by her mother – the grandmother who slept a lot – that “she would never be a very good mother, so she shouldn’t even try”.

Stadlen’s own mother was progressive in some ways and endearing in others, but found it hard to relate to people who weren’t like her (Stadlen among them) and didn’t appear to read much of her own daughter’s first book, dismissing the first chapter as “anecdotal”.

Stadlen was determined to do things differently. “I wanted to prove that you could bring up children in a trusting way, and that they’d be worthy of that trust.”

She has also married two words – mother and love – that seem almost unfashionable in “childcare” literature. There are books galore on how to “deal” with your children, how to control them, make them fit into a routine. There is even one, which has sold over half a million copies, that tells you how to physically punish your child. But understand them? Comfort them? Dirty words. Stadlen is resoundingly unapologetic about the word mothering, too. “Everyone says ‘parenting’ these days,” she gently chides, as I tell her an anecdote about a mother, but use the word parenting. “What’s wrong with the word mothering?” I think about this for days afterwards. It’s a word I hardly hear. I start using it. It’s such a lovely word, after all, so comforting, so without substitute.

But she hasn’t written a “how to” book. It’s simply, but complicatedly, a book about love. “I’ve tried to show how love is much more than a feeling inside you, it’s a communication of love to your child.” Stadlen explains. “The love inside you seems to generate huge resources of energy, so that you can do a lot for your child. It’s the doing that communicates the message. That’s what I wanted to show.”

A clue to what the book is really about is in the subtitle, “and how relationships are born”. It’s about how crucial a mother’s love is in shaping a baby as a human, and why mothers are therefore vital in society. “Mothers enable people to relate to each other in different ways. Without mothers we would all be separate, different units.”

Can a mother ever be replaced?” “Well, yes. People do their best with what they get, but it’s simplest if mothers can do it and mothers realise that they’re doing it.”

The key to this is the special, often silently communicated, intimacy between a mother and her baby. “Intimacy is crucial for a person to realise his or her potential to the maximum. It enables a person to reach genuine original, loving and creative energy. But intimacy can feel very risky if one has been hurt by early experience of it as a child. Mothers do not seem to recognise their importance in being able to introduce or inhibit this whole dimension for their child.”

Yikes, you might be thinking, is this book going to make me feel guilty (this is what Stadlen’s mother asked)?

In fact, I think it would be hard to find a gentler, less judgmental book on mothering. “I think that with mothering you can always put things right, make things better, right until the last minute. Children are much more generous than parents seem to think,” she says.

Stadlen was born in London. Her parents were German Jewish refugees. Her father was a graphologist and training to be a psychotherapist when he died of a heart attack, the same week Stadlen’s younger brother was born. Her mother was left with two children under three, 10 shillings and very little support. “My mother didn’t remarry, so I didn’t have much direct experience of fathers, but when we [her and her husband Anthony] had children I realised how desperately important fathers are.” Stadlen’s mother died, aged 97, in 2005.

Stadlen studied European history at university, then became a psychotherapist via careers as a book editor, occupational therapist and social worker. She became a mother, to a daughter, for the first time aged 28. She found motherhood shocking, but in a good way. “It was totally different to how I expected it to be. I didn’t expect her to be so conscious. Straight away we were in a communicational dialogue, which was very exciting, very demanding. Everything babies do is meaningful, not pointless or random.” Two more children followed over the next 11 years.

Stadlen, the woman, is small, and quietly spoken (she does tai chi – “being strong without pushing”). She sits in her husband’s consulting room (he is also a psychotherapist) with stalagmites of books and notes, in a circle, at her feet. As I leave, I ask what they are for.

“In case you asked me anything, and I needed to refer to them,” she answers. What possible question would she not know the answer to, off the top of her head? I get the feeling that Stadlen sometimes doesn’t think her own words are enough. Her book makes heavy use of quotes from mothers (anonymously), which are interesting and relevant, but I think they sometimes shadow Stadlen’s own words. She often lets other people’s words shout over hers, so that her own very good points are sometimes eclipsed.

“I think you’re probably right about that. I don’t shout.” Stadlen also, more than once, tells me about the mail she gets from all over the world (about her first book), with mothers saying it validates how they feel. But I wonder if these responses also validate her work. This would make sense, given that what we’re talking about – mothering – isn’t, sadly, regarded as the most important job in the world.

Yet I have personal experience of Stadlen, where she has been more forceful. I went to see her once about an aspect of mothering I was finding very difficult. I was in a mess and booked a double session with Stadlen, the psychotherapist. After 100 minutes, during which she can’t have uttered more than 50 words – but what words – it was as if she had picked me up from the path I was heading down and placed me on another one entirely. The effect – the session was nearly two years ago – still hasn’t left me and the results were profound. She changed not only my life, but also that of my children.

Perhaps this gentle approach in her books is partly because of one of her bugbears. Scientists or baby “experts” – often childless ones – ruling a generation of mothers with advice based on no evidence, yet they are listened to because their opinion is regarded as more important than a mother’s.

Stadlen distils mothering down to two styles. Very cleverly calling them “Spartan” (routines, making your child fit in with social expectations) and “Athenian” (listening to your child, understanding them). Stadlen has no desire to tell mothers how to “be”, she is adamant that each mother-child relationship is unique. Even when I press her – “Yes, but how would you deal with this?” – she sidesteps with questions. Although I find this annoying, I’m also grateful that she isn’t another “expert” telling me how to raise my child. “I am very keen to try to find something universal in mothers that keeps us all together. There’s so much divisiveness between mothers.

“For too long, mothers have let other people dominate the way motherhood is framed and seen and now, for the first time, there is a much bigger generation of mothers who are educated to question all these things that have been said about them. But they don’t. You have these people say to you, ‘I’d rather be nice to my baby than not, but the books tell me I’m not a firm enough mother.'”

Whereas what mothers do is actually more scientific – and less anecdotal – than they realise.

So what sort of mother is Stadlen? “I’m a listening sort of mother. I realised that if you listen and watch your children, they will tell you things. It took me a long time to work it out. I’m not a perfect listener, not ideal in any way, but I realised that it’s an exchange. Mothering is a real communication between two people.” And has she been successful? “I have achieved what I wanted to do, but I don’t know how you measure success. My children have proved they were worthy of trust, more than I ever dreamed.”

It is a shame that Stadlen isn’t the sort of woman to have her own “parenting” TV show. I can’t imagine she would ever want to, or be asked to. Because what she talks of is so quiet, as to be almost invisible. To the onlooker, it might look like nothing. And yet it is everything.

How Mothers Love and How Relationships are Born by Naomi Stadlen is published by Piatkus, £13.99. To order a copy for £11.19 with free UK p&p, go to guardian.co.uk/bookshop or call 0330 333 6846.

This article was first published in the Guardian Family section.