A monk was instructed by his teacher to meditate for exactly forty-five minutes. But the monk didn't have a watch or a clock to use to time himself. At realizing the monk's problem, his instructor handed the monk two incense sticks that each take exactly one hour to burn. The incense sticks however are not identical, and they each burn at a non-uniform rate, since after all they are hand-made. Using these incense sticks and some matches, how can the monk arrange for exactly forty-five minutes of meditation?