If it is true that the most difficult thing in life is to know thyself, as Greek philosopher Thales of Miletus once stated, actor Isaiah Washington is living proof.

Washington gained widespread fame for the role of Dr. Preston Burke on the award-winning drama, "Grey's Anatomy," until he became infamous for a 2006 dust-up with cast mates. Since departing the show in 2007, the actor has devoted himself to a new endeavor:  restoring the nation of Sierra Leone to its former glory.

The details of this ambitious task are the subject of Washington's new book, "A Man from Another Land: How Finding My Roots Changed My Life," with Lavaille Lavette (Center Street, $25). Washington has a Sunday book signing in Atlanta.

In 2005, just a month before the Houston-born actor would beam into millions of homes as Dr. Burke, Washington received a gift he welcomed. As a Pan African Film Festival award recipient, Washington was asked to take a DNA test to reveal his African ancestry. The test showed his maternal ancestry to be the Mende and Temne people of Sierra Leone and his paternal ancestry to be with the Mbundu people of Angola.

"This DNA thing can give us all a lot of answers to our personality, likes and dislikes and how we can respond to certain stimuli," said Washington, who was granted full citizenship to Sierra Leone based on his DNA testing. "Particularly as African Americans, we have to figure out how to take what we learned and take it back to the motherland."

Inspired by this tangible scientific link, Washington said he plans to "reverse the middle passage of Africa." Describing it as his life's purpose, Washington details in the book his efforts to build a school in Sierra Leone through his non-profit organization The Gondobay Manga Foundation. He documents the journey not only in the book, but also describes filming his several trips to the formerly war-torn nation.

During his first visit to the country in 2006, he was inducted as an honorary chief. It was the culmination of a dream Washington had experienced since 1972, when he would run from something until he found himself in an African village. When he became a chief, the recurring dream stopped, he said.

On his path to chiefdom, Washington faced his share of struggles. After leaving the Air Force, Washington made an ill-fated attempt to attend college at Howard University. He left after one semester and would soon head to New York, where he embarked on a period of self-discovery that involved cowrie shells, dreadlocks and other trappings of '80s Afrocentrism. As an actor, his early projects weren't blockbusters.

"The reason I am not a multimillionaire is I was choosing movies to send a message about who we are as a people," Washington said. "I have always been using my acting as a Pan-Africanist. I have always been getting people to think about who we are. I love my people even when they don’t love me."

When a well-publicized argument with his Grey's Anatomy co-star, Patrick Dempsey occurred, Washington was enmeshed in his efforts in Sierra Leone. He had become an African chief, attending the induction ceremony in the lucky scrubs he often wore to portray Dr. Burke on TV. He had assisted doctors in medical procedures for children, put out a fire in a hotel and even investigated the impact of the diamond trade, he said.

But none of that could prevent the fallout from his altercation with Dempsey over comments made earlier in reference to T.R. Knight. For a year, Washington denied his actions, apologized for them, entered therapy and ultimately left the show. When he looks back on it all, he cringes.

"I didn’t put it in the book, but I wish I had," Washington said. "One of my mom's cardinal rules was, ‘Mickey, don’t argue with fools.' When you argue with fools the people looking at you will not be able to tell the difference. I let that teaching slip and got off message.

"Had I known then what I know now, about me, I probably would have been able to just walk away from Patrick and say, ‘Man you need a nap.' As painful as it was and sometime still is, it is what it is."

Since then, Washington has had his share of hard times with the discovery in 2008 that he was bankrupt. The acting jobs have slowed, and he isn't sure what he's doing next, but he remains prayer-minded and convinced he is on the right path.

"History is in the making and it is going to spread," Washington said. "There is nothing we cannot do if we put our minds to it. We as a people come from that kind of richness."

Event Preview

Book signing, "A Man from Another Land," by Isaiah Washington with Lavaille Lavette (Center Street, $25)

3 p.m. Sunday. Free.

Barnes & Noble, 2900 Peachtree RoadN.E.

404-261-7747. www.barnesandnoble.com