We're here to talk about the first Mercury Rev LP in seven years, The Light In You. It's the ninth since the band's inception in 1989 but the first where Donahue and guitarist Grasshopper - aka Sean Mackowiak - life-long friends, have been let loose behind the controls, with Rev bassist and legendary producer, Dave Fridmann, stepping away from the mixing desk.

Donahue expands on this idea of working with old friends. He hasn't really ever known much else: he describes his time with Flaming Lips (on In a Priest Driven Ambulance and Hit to Death in the Future Head) as being an older brother / younger brother type set-up with Wayne Coyne, and it seems to have been a help rather than a hindrance:

"I've never been in a situation where it's been like, cantankerous. Emotional maybe, but never where I've not wanted to be in the room with that person. I don't think any of us have - we record with people we love. We wouldn't do it otherwise."

And how about producing the album without Fridmann, whose schedule and distance from Donahue and Grasshopper, both based way up in the Catskill Mountains (home to Woodstock Festival), meant he couldn't take his normal role at the production helm?

"We all started in music together, so him not producing was a bit like three girls usually going to the bar together and then one night one of you can't make it" he says.

"...we record with people we love. We wouldn't do it otherwise."

"It doesn't make the night bad - it's just different. You have different laughs and different conversations. And that's what it was like in the studio. The same thing but in a different light."

It's now that I realise Grasshopper's still not with us - when I want to see the face-to-face interplay between these two old friends - and I'm told he's still in his room after a long night at the hotel bar, he didn't realise the interview was scheduled.

They may have been going since the 1980s but these guys still give good rock 'n' roll.

More than twenty years together has brought certain changes. Donahue says they don't talk very much in the studio anymore; they just play and listen. "When you're younger you really want to chisel out where the songs go - you see them as a block of marble to chip way at" he says. "But when you get older you listen to where the song itself wants to go."

He says he thinks of the process as "listening" to a record rather than recording one. "I know it sounds strange, but the best songs come in twenty minutes, often."

Donahue talks about the age thing too; increased life-experience. "When you're in the 50 category your parents change, life and death comes at you quicker than when you're 21 and everyone around you and your world is stable," he says. "Now, death flies at you in different ways, life happens faster."

He thinks it's improved their song-writing and craft, rather than hindered it: "Our peers around the same age, you can see a different light in their eyes, and real life in their songs - not just the violent imagination of a 21-year-old, thinking you know things."

I wonder what on the record has been informed by this shift, this change in feeling and outlook? "Everything I think" he says, dreamily rather than vaguely. "It's about the death of a lot of things, things you thought were solid - relationships, people, your own identity even - you think that'll be with you for many, many years but then it gets melted down.

"Fortunately I'm a writer, so I can use my music to exfoliate that, smooth it down."

As well as metaphorical rebirth, Grasshopper has actually become a father in the last year. Peppered throughout the LP are lullaby-ish bells and sweeping fairyland harps. When I liken these to nursery rhymes, and wonder if this reflects Grasshopper's new fatherhood, Donahue says: "You hit a bulls-eye, no-one else has noticed that yet."

When we speak later, Grasshopper himself says, "I've been asked in the past when Mercury Rev would do a children's album, and I've always said, 'Well, all of our albums are children's albums.'

"So, I guess having a child - and Donahue is godfather to my boy - has had a sub-conscious impact during this record, although it has been a constant Mercury Rev theme to see the world through the eyes of a child, in a type of Zen perspective."

On The Light In You the notion of death and rebirth seems to manifest itself, lyrically at least, in metaphors using nature. Donahue says this is the only way he can write: "Naturally - pardon the pun - it's the language I understand. It really means there's something going on inside of me. It's programming language to me - it's the best way I can describe to anyone else what's going on inside."

"The seasons, and how they change, and what that means in life. I could never get onto the 'Baby, baby, baby you broke my heart' simplicity of that sort of song writing or romance, so I grew up with metaphors - the leaves are falling, something's going on inside me too."

You can hear this on "Autumn's In The Air": "The wind begins to trace / The many lives I've tried to paint... Parts of me erase / One by one they disappear."

"I have bears. My hold-up isn't a track fire on the subway, it's a bear, or a row of turkeys crossing the road and you can't move for 40 minutes."

It's no wonder this is his language. Born in the woods and now living up in the Catskills, Donahue is surrounded and submerged by a raw, sometimes inhospitable nature. "The way you guys here in London have to navigate an urban landscape - people on the street, people you work with - I don't have that" he says, smiling.

"I have bears. My hold-up isn't a track fire on the subway, it's a bear, or a row of turkeys crossing the road and you can't move for 40 minutes."

The often ethereal sound - all sweeping strings and Christmassy bells - belies the record's earthy, natural thread: girls play soul on the jukebox, dolphins leap, rivers are gazed into. A very 'worldly' world is created, complete with sunflowers, moths, leaves and forests, but behind them lies a fairy-godmother female backing vocal, which leaves you wondering if you're in a dream or the real world.

The elusive "light" of the album title too is otherworldly, but to Donahue it seems very much real. "The melting down process of change is fascinating, it's hard to see the positive while you're going through it sometimes but on your way out you have a lightness, that light in you, " he says, seemingly unaware he's almost quoting the album's title.

"That lamp when everything else around you is dark and you can't see out of it or even through it - I don't know where it is or what turns it on, but I've noticed it a few times - and I'm sure you will too. Everyone goes through those times, you cant see forward, when uncertainty is bigger than your mind can wrap its head around."

Specifically he remembers this light when going through his drink and drugs spirals. "It's not loud when you hit rock bottom, it's not a giant fireball like everyone imagines it's gonna be. It's more like landing on the moon" Donahue says, showing glimpses of his psychedelic imagination.

"It's not loud when you hit rock bottom, it's not a giant fireball like everyone imagines it's gonna be. It's more like landing on the moon."

"You look around you and all the parts of the spacecraft that brought you there - that could've got you back up again - are all broken. And you think, 'There was a wonderful relationship I had, and it's broken. ' Or, 'There was a great part of me, that's now twisted.' But that inner lamp goes on and lifts me up like a flotation device."

He says he found the band's seminal 1988 recordDeserter's Songs like this: "I was messed up before that record, it was on the way back up that I found Deserters Songs." The lyrics to "Coming Up For Air" almost mirror this experience: our narrator is left shattered in pieces, only to regroup and swim back up the surface, coming up for air.

He describes the entire album, its highs and lows, as "one man just sort of staring back at that" resurfacing, that light turning off and on, accepting the bad times rather than resenting or judging them.

He talks - Buddhist-like - about the importance of this acceptance, not dragging the heavy negativity of the past with you: through acceptance you can carry your history with you, but not as a chain around your neck. Donahue (and it doesn't surprise me when he brings it up), lives right next to the largest Buddhist monastery in America, the Karma Triyana Dharmachakra: "Probably some of that is drifting through, in the way that there's an acceptance of experience - maybe that's what all my music is about."

When I ask if Buddhism is something Donahue practices it seems more than something that just drifts over the walls of his garden: "It's a bit like asking someone if they like health food - I do, actually, I don't really wanna put crap in my mouth."

"Buddhism works, in just what it asks of you, maybe best of all the mystical religions. I don't sit down in the middle of the forest at midnight and 'om shanti', but I have my own way of doing it - so do you, I'm sure - it doesn't necessarily mean sitting in the lotus postion or doing yoga, it's just standing outside of that framework called 'you'."

Donahue is equally as philosophical when it comes to how the record is perceived, and genuinely interested in how others experience it. "I can see it reflected back at me in the people I'm talking to about it now" he smiles. "I'm listening far closer to what you say about the album than you probably think. I'm like a bat, picking up pings off of you!"

"The stars aren't out there until someone sees them."

I assume he is used to the idea of strangers interpreting his work by now, and he's back to the insightful metaphors that have characterised our conversation, as well as The Light In You: "It's a bit like bringing your baby or your puppy to a party - you want everyone to say it's the most gorgeous one they've ever seen, but there's always someone at the party saying 'Ah, it's just another puppy' or 'Oh look, that baby's crapping in the corner'."

"There's always that anxiety that something you hold so dear and have spent so much time on will be mediocre to others. And with reviews, if I believe the good ones then I have to believe the bad ones..."

This is definitely the side of the album process that Donahue takes the least joy in - the promotion, the touring - especially now, he says, when the pace of the industry seems to increase yearly. Every trip down from the hills requires a greater shift in gears.

"I'm not that enamoured with the pace" he laughs. "I could have easily handed in the record and headed back up the mountain. Grasshopper's the one who's great with it, he's really built for that life. I'm more like a reluctant knight, saying 'Here we go then, another quest!'"

And even though he's smiling, I'm left with the feeling that Jonathan Donahue really can't wait to get back up that magical mountain where he belongs. Back to that light.

The Light In You is out now via Bella Union. Buy on iTunes or Amazon.