"I am extremely exalted," she told the dozen or so journalists who had managed to track her down on hearing the news from the Nobel Committee in Oslo, as the hotel's tourist guests and professional entertainers listened in.
"I thank God and my ancestors for this award. This is a great honour for me and my fellow environmentalists who have suffered together over the years," she said.
Maathai's defence of the environment and of the human rights of Kenyan citizens has landed her in jail and won her quite a few bruises from police truncheons over the years.
"This is a very exceptional moment. It means that work will be done better and harder," the 64-year-old Maathai, the first African woman to win the coveted peace prize, said.
The Outspan Hotel's setting was apt for the occasion. It sits in the shadow of Kenya's highest mountain, which has been ravaged over the years by loggers and marijuana growers. Maathai has dedicated most of her adult life to replanting her country's forests and others in Africa.
"After receiving a call from the Nobel Committee this morning, I looked at the mountain, cried and recalled stories that my parents told me about how ancestors reward people who genuinely work hard for a genuine course," she mused.
"This mountain has inspired me for several years. That is why I worked very hard to protect it. I have not succeeded but the struggle continues," added Maathai, who planted a Nandi Flame tree at the hotel and posed happily with tourists, delighted to rub shoulders with a Nobel laureate.
The Green Belt Movement which she founded in 1977, has planted some 30 million trees in Africa, its way of opening the way to community development.
"She is a true Kenyan hero. Her humbleness is amazing. She deserves every bit of the award," commented a tourist from Switzerland.
Asked what she would do with the million dollars that come with the prize, Maathai, Kenya's assistant environment minister, seemed baffled.
"Oh my God, I have never seen such a large amount of money, I need to budget, but either way, quite a large amount will go to the protection of the environment."
"Through me, African women who have struggled have been paid back. I will continue with my work as an environmentalist, nothing will distract me," she said.
"This has just renewed my impetus. It is time for action, and not mourning how poor we are, leaving the environment in utter ruins," she said.
"I am not going to abandon my career. I will carry on with until I see that the environment has been protected," she added, before boarding a modest van bound for her nearby parliamentary constituency.
Word had already reached Ihuroro, a village in her constituency, that their lawmaker had won international recognition — and a million dollars — for planting trees.
"If that's the case, we should all start planting trees," one villager told AFP.
AFP