to demonstrate Vovinam publicly in Hanoi with his disciples in 1940, Nguyễn was invited to teach the art at Hanoi's Ecole Normale, and Vovinam gained in popularity. During the following years, political unrest increased throughout Vietnam; due to the system's nationalist political orientation, the art came under suppression. By 1954, Nguyễn had emigrated to South Vietnam, where he was able to continue to teach and establish Vovinam schools. After his death in 1960, Grandmaster Lê Sáng continued the development and international promotion of Vovinam until his own death on September 27, 2010. The first Vovinam school outside of Vietnam was established in Houston, Texas, by Vietnamese emigrants in 1976, after the Fall of Saigon. By 2000, Vovinam schools had been established in Australia, Belgium, Canada, France, Germany, Italy, Morocco, Poland, Spain, Switzerland, and the United States. Vovinam now exists as Vovinam Việt Võ Đạo, without the political overtones it originally carried. Logo The Vovinam Việt Võ Đạo logo is framed in a yellow shape composed of a rectangle conjoined with a circle, angular at the top, round at the bottom. This shape symbolizes the perfection of the hard and soft. Within this yellow shape, the red text "Vovinam" is written above the marine blue text "Việt Võ Đạo". Beneath the text appears a Âm-Dương symbol in red and marine blue. The Âm-Dương is surrounded by a thick, white circle, symbolizing the being of the Dao, with the mission to mediate between negative and positive (Âm = Negative, Dương = Positive), to subdue the two, to enable life of all beings. A yellow map of Vietnam is superimposed on the symbol. Theory Hard and soft The yin and yang theory (Vietnamese: "Âm-Dương" and "Nhu-Cương") states that everything in the universe and on earth is initiated through the interrelation of Âm (negative) and Dương (positive). As to this theory there are martial arts that prefer the hard over the soft and others that prefer the soft over the hard. Vovinam Việt Võ Đạo does not prefer any over the other. Hard and soft are used equally to adapt to every situation, to every problem. Based on Võ-Thuật, the student aims to develop the ability to combine hard and soft in combat and in daily life. This aims to develop physical abilities as well as the student's spirit. Not only the principle of the harmony of hard and soft but also many other