I would say the ideal posture for sitting meditation would be the cross-legged posture, but even in the cross-legged posture there are variations, like the lotus posture is one type of posture; half-lotus is another. But with whatever posture you choose, it is important is to have your spine erect, because when you have your spine erect it is very easy to become alert and awake and really be conscious. So this is where sometimes yoga exercises can help you to work with your posture. And here again what is important is to have a posture where you can feel relaxed. This is very important. To be mentally and physically relaxed when you meditate is extremely important.