"Various people have offered different explanations for the name tai chi chuan. Some have said: 'In terms of self-cultivation, one must train from a state of movement towards a state of stillness. Tai chi comes about through the balance of yīn and yáng. In terms of the art of attack and defense then, in the context of the changes of full and empty, one is constantly internally latent, not outwardly expressive, as if the yīn and yáng of tai chi have not yet divided apart.' Others say: 'Every movement of tai chi chuan is based on circles, just like the shape of a taijitu. Therefore, it is called tai chi chuan.' Both explanations are quite reasonable, especially the second, which is more complete. ... Those who practice shaolinquan leap about with strength and force; people not proficient at this kind of training soon lose their breath and are exhausted. Tai chi chuan is unlike this. Strive for quiescence of body, mind and intention. ... Scientific principles could apply to every aspect of tai chi chuan skills. Even more, the ways that empty and full transform are unfathomable. When practicing the form, the entire body feels comfortable; when pushing hands, the entire body feels lively. Therefore, after a long period of constant practice one not only avoids being tired, but actually feels more spirited after doing tai chi chuan. This indicates great intensity of delight. However, beginners, who have not yet grasped the fundamentals, must go through a period of forbearance. Then, eventually, they will spontaneously enter the most enjoyable stages."