"On the whole, the life of a chess professional is not as easy as it appears at first sight. One needs to devote some ten hours a day to chess and to everything connected with it - physical and psycholgical preparation."

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First and foremost it is essential to understand the essence, the overall idea of any fashionable variation, and only then include it in one's repertoire. Otherwise the tactical trees will conceal from the player the strategic picture of the wood, in which his orientation will most likely be lost.

— Lev Polugaevsky