When Robert Smythe founded Mum Puppettheatre in Old City in 1985, it was just about the only way he could find work; puppetmaking and puppeteering then were at the extreme edge of theatrical consciousness. Now, 23 years later, Smythe has resigned as Mum's artistic director and guiding force, and puppets are a bona fide part of the stagescape.

Still, theater companies devoted solely to puppetry - or, more likely, to a mix of live actors and puppets - are not popping up everywhere. Mum, at 115 Arch St., has been a pioneer that helped to open stage doors for puppeteers around the country. And until now, it's been all but synonymous with Smythe.

"What I've realized," explained Smythe, 47, whose midweek resignation became public Thursday, "is that in order to be the artist I am and want to be, and still have the potential of becoming, I don't need to be running a theater. I'm not leaving in a snit," he stressed, "there's no animosity."

He did leave abruptly, though, during preparation for a show,

The Adventures of a Boy and His Dog in Ye Olde Philadelphia

The three-weekend run, which had been scheduled to begin at 2 p.m. today, has been canceled.

Smythe said his move would give him more time to spend with his family, including a daughter and son. "My daughter's 16, and we never had a real Memorial Day," he said, because he's always been preparing for a show.

He said he'd been thinking of moving in different directions for a few years, and that the time was right. Two years ago, Mum implemented a new management strategy and hired its first managing director, who brought in a team. "Over the course of two years we've been trying to figure out how a company working in one direction for 21 years needed to change and adapt and move forward.

"Over time, I realized I found myself not always in agreement with choices being made and decisions about what the future should be. About a month ago, I actually was ready to resign and at that point, we were working with a management consultant who, as part of developing a strategic plan, said: 'You've got a lot invested in this company, so let's see if we can work this out.' "

Ultimately, they could not. For the last two years, Smythe has been a Pew Fellow in the Arts, an award that provided $50,000 and "a transformative experience," he said, that forced the question, "am I an administrator or am I an artist?" The administrative part, he decided, gave him a been-there, done-that feel: "I'm not there anymore."

This fall, Smythe will become a two-year fellow in playwriting at Temple University's theater department.

He said he was particularly proud of Mum's nurturing of artists over his decades at its helm. Two current, highly visible examples are local puppet designer and actor Aaron Cromie, now in the cast of Philadelphia Theatre Company's

The Happiness Lecture

with Bill Irwin, and the young Philadelphia actor Tobias Segal, earning kudos in the Manhattan Theatre Club's

From Up Here

, for which he received a Drama Desk nomination.

Next week, the nationally recognized Smythe will teach at the O'Neill Puppetry Conference, at the Eugene O'Neill Theater Center near Hartford, Conn., and he hopes to branch out in other ways. "Over the past years," he said, "I've had to say, 'No, I can't actually do that. It doesn't fit into the plans at Mum Puppettheatre.'"

Contact staff writer Howard Shapiro at 215-854-5727 or hshapiro@phillynews.com. Read his recent work at http://go.philly.

com/howardshapiro.