Many people find freedom a difficult word to define until they have lost it.

For men like Bill, an inmate at the State Correctional Institute at Rockview, the idea of freedom is like an existential dilemma -- constantly occupying his mind and threatening to drive him mad.

A 45-year-old baby-boomer who came of age politically in the 60s, Bill measures his incarceration in terms of what he has lost -- a small bookkeeping business, contact with family, intellectual conversation and, most importantly, time.

"One is conscious of every day," he says from a worn chair in the institution's visiting room. "Time definitely drags."

Bill is one of 1,928 men in Rockview who spend their lives behind locked doors and barbed wire fences.

The total national number of inmates has more than tripled since the early 1970s, says Tom Bernard, associate administration of justice professor. He estimates that state and federal institutions now hold about 700,000 prisoners.

In Rockview's visiting room, other inmates and their families or friends are scattered about, holding hands or talking, attempting to cram every second with life.

Paintings of snow scenes, wildlife and Walt Disney characters line the walls of the room. These paintings, which range from notebook size to more than four feet tall, were created by the inmates and can be bought by visitors.

The entire room, including its worn floor, mismatched furniture and faded signs, appears old, as if nothing has changed since the 60s.

Bill, who asked that his real name not be used, says he has not received a visitor since he "went down," or entered prison, one and one-half years ago. His 77-year-old father, his only living relative, cannot make the trip across the state.

The heavyset inmate shifts uncomfortably in his seat while divulging his sentence -- five to 10 years. The time weighs heavily on his mind.

"I keep a record by quarter year," Bill says. "Every quarter I say, 'I've got so much time now.' "

"I tried measuring it in months but that didn't work, they move too slowly," he adds.

Bernard says when a person is placed in a situation where all decision-making is taken away, the person becomes like child, unable to assert control over his or her life -- a process called "institutionalization."

"The more severe the sentence, the greater loss of a person's ability to readjust to the external world," Bernard says.

After Bill was convicted for his crime, a sexual offense, the prospect of his first trip to prison drove him to a suicide attempt. He spent four weeks in a mental institution and now receives anti-depressant medication, visiting a psychiatrist once a month.

Occasionally, though, he still becomes very depressed. Thoughts of lost time and a changing world creep into his daily routine.

"It's even worse because you're going to have to go back out there and you're not going to know what's changed," he says.

In addition to the medication, which he hopes to eventually discontinue, Bill has found other means to cope with depression.

"I've discovered when I read history, I can pull myself out of it," Bill says. "I can sink into whatever period I'm reading about and, except for going out to meals, I can see nothing later than say 1350."

This interest in history came to fruition early in life, when Bill received his undergraduate history and political science degree in 1965 from St. Peter's College in New Jersey.

Recently, he has been reading about the Revolutionary War and Medieval Europe. Beyond the pleasurable aspect, Bill claims these readings serve as mental exercises, adding "I don't just read these books, I take notes on them."

But academic pursuits cannot alleviate all of the realities of prison, such as a diminished communication with the outside world.

"My father's out there on his own; his health is deteriorating," Bill says with worry in his voice.

The inmate's speech quickens, fueled by the possibility of losing his only family member while he remains behind bars.

"He can't deal with insurance. I mean he's intelligent but finds it hard to do," Bill says. "I used to be the one to take care of things like that and I can't anymore. That bothers the hell out of me all the time."

Bill seems shaken when he talks of his father -- he tries not to think about these things. Regaining his composure, he says, "It's particularly hard to maintain contacts with the outside."

He writes home about twice a week; each envelope bears a tell-tale space for the prisoner's "Number:" in the pre-printed return address.

He also writes about one letter a week to his girlfriend. "We met while in the mental health unit," he says. "We saw each other occasionally before I came in in July."

But the inmate says he would rather communicate by phone, a luxury made "awkward and expensive" by the circumstances of incarceration.

Bill describes the procedure in a droll staccato. People on the outside cannot call in, he says with disgust, and inmates receive one 15-minute collect call per day for which they must sign up in advance.

Although Bill and his father arrange to speak every other week, the process sometimes proves unsuccessful and nearly always frustrating.

"How many times do you call someone and they're not there, or you get their answering machine?" he asks.

"If I'm scheduled for a specific time, like 3 o'clock, and they're not there, well fuck my rotten luck," Bill says raising his voice. "You can't wait a half an hour because someone else has signed up for that time."

Communication through the mail also inevitably reminds Bill of his lost freedom, making him upset with his situation and himself.

"I never get a sealed letter," he says. "Mail is searched for contraband and content, too."

Rockview is classified as a minimum to medium security prison, said Jack Allar, administrative assistant. The correctional institutions at Pittsburgh, Huntingdon and Graterford provide maximum security incarceration, Allar says.

Money orders make it through to inmates, but cash is immediately transferred to inmates' personal accounts. Allar says inmates are not permitted to have cash, and any money they earn from their jobs also is transferred to their accounts.

Seemingly banal tasks for a free person, such as receiving a renewed driver's license, become reminders of freedoms revoked. Bill says he had renewed his license before coming in, but officials transferred it to his personal property box before he was able to see it.

"It's in a filing cabinet somewhere, I suppose."

Even religion suffers the constraints of an institutional environment. During weekday visits to church, Bill, a Catholic, must give his inmate number at the door of the chapel so corrections officers know he is there.

"I have to be reminded every time I go there," he says. "It never becomes (a natural) part of my going to church."

The institution does have a library for inmate use. An avid reader, Bill sees the library as one of the "high points" of prison. But inmates cannot browse through the stacks and must randomly peruse the card catalog to encounter subjects they might find interesting.

Allar describes Rockview's inmate programs as "very good." Inmates can take Penn State undergraduate and Pennsylvania Business Institute courses in addition to high school level courses.

"For a prison, there's a lot of educational and vocational opportunities (in here)," Allar says. "For (Bill) there's not much more we can offer him. He's far better educated than most of the general population."

When an inmate first enters the general population, he is assigned to an educational program. Some prisoners work toward the equivalent of a high school diploma. Bill now spends one hour a day in bookkeeping classes.

Although taken for personal benefit, parole boards often look favorably on such courses.

"These things are all technically voluntary, but (prison officials) encourage you very strongly to take some schooling," Bill says.

Bernard says the prospect of parole motivates inmates to de-institutionalize themselves.

"As people move toward the end of their sentences, they tend to reassert more control over their lives," Bernard says.

The possibility of parole also enforces inmates caution to maintain "good behavior."

"Anything an inmate does during his stay in jail, positive or negative, is written up in a report for the parole board," Allar says.

Allar says while the institution makes recommendations for inmates parole on its report, the final decision rests with the state's parole board, an entity independent of the prison that follows orders from the governor.

Inmates regard the official term of "misconduct" as a write-up, Allar says.

"It's always in the back of your mind: 'Is this going to get me a write-up?' " Bill says.

"For example, you can't have anybody who doesn't live in that cell, be in that cell at any time. Occasionally, people come by to bullshit and you forget about these things and . . ." Bill shrugs his shoulders in a helpless gesture.

Inmates' families slowly leave the visiting room. C.O.s lead the inmates back to their lives, back to count the days, months or years.

Bill speaks hopefully about his release. He says he could be paroled by the summer of 1993 at the earliest.

Bernard says the public conceptions of prisoner recidivism are distorted.

"A larger number of (prisoners) are able to readjust than most people think," Bernard says. "Some people coming out of prison are going to be motivated to stay out."

Bill says he has plans to restart his bookkeeping business and believes the people he worked for might want him back.

"I'll be close to 50 when I get out so there's no point in looking for (other types of) work," he says fatefully.

In the meantime, his days will be filled with history, and work, and classes and lost time behind the walls and green barbed-wire-topped fences of incarceration.