Mainly in laying down a good foundation of its theories through the founders’ studies and writings, many of which have become tai chi classics recognized by all styles. To quote from one of T’ai Chi magazine‘s FAQ’s titled “What are the t’ai chi classics“*:
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The classics are generally referred to as: The Theory of T’ai Chi Ch’uan by Chang San Feng (Zhang Sanfeng), The Classics of T’ai Chi Ch’uan by Wong Tsung Yueh (Wang Zongyue), An Internal Explanation of the Practice of the 13 Postures by Wu Yusiang (Wu Yu Xiang), The Five Words Secrets by Li Yi Yu (Li yiyu), and Summary of the Practice of T’ai Chi Ch’uan and Push Hands by Li Yi Yu.
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In fact the oldest (credible) classic mentioned above, The Classics of T’ai Chi Ch’uan by Wang Zongyue, was actually discovered by Wu Yuxiang’s brother, having received it from his subordinate while serving as a local government official. His subordinate tried to please him, knowing his enthusiasm for this martial art, with the scroll they discovered by chance.
*[Ed. According to tai chi scholar Gu Liuxin, tai chi writings pre-dating those of Wang Zongyue, such as those by Zhang Sanfeng, are not credible. Bold types added by the editor. ]