Chih-i illustrates the five meanings of sūtra (in the view concerning the word sūtra as translatable) with reference to the mind contemplation. …
In terms of the mind that is related to the meaning “wholesome teaching”, this means that mind can be taken as the teaching of wholesome words. Mind can also be taken as the teaching of wholesome practice, and wholesome principle. Thus, mind can be extended to contain the meaning track, constancy, and facts.

1. In terms of the mind as track, Chih-i explicates that if there is no contemplation, there is no rule to follow. Because of correct contemplation, mind is in charge. Because of the mind that is correctly in charge, the intention in the mind is also correct, so are practice and principle. If the mind that is in charge tallies with the principle, the intention also tallies with the principle. Therefore, mind can be regarded as track.
2. In terms of the mind as constancy, Chih-i explains that the nature of mind is constantly in concentration, which is like empty space. Such empty space cannot be ruined. Evil consciousness cannot ruin wholesome consciousness, deviant deeds cannot hinder correct deeds, and deviant principle cannot break correct principle. Therefore, mind is regarded as constancy.
3. In terms of the mind as facts, Chih-i explains that everything directing at the mind is taken as contemplation. The accomplishment of the contemplation of wisdom is not in contradistinction to the facts. This is like the fire that aids firewood: the facts and principle are not apart. Written language is contained in nonwritten language. One does not abandon written language in order to contemplate one’s mind. (Vol. 2, Page 398-399)