Let us first review the main theme of the sūtra itself: The three vehicles do not exist; in reality there is only One Vehicle, meaning that “there is only one form of Buddhism.” Hurvitz nonetheless draws out two component points. One is that “there is only one Path to salvation, not three.” The other is that “the Buddha is not to be delimited in time or space, or indeed in any finite terms.” The first point portrays the three vehicles as a device to attract beings to Buddhist practice. In the sūtra, this first theme is dominant and has more significance, being illustrated by four parables (Chapters 3, 4, 7, 8). The second theme is confined to only two chapters (16 and 17; in the [Tao-sheng’s commentary], 15 and 16) and is supported by one parable (Chapter 16)

In the [Tao-sheng’s commentary], no theme is more pronounced than the three-One relationship. It is certainly the central leitmotif of the text. This is evident from the start. Every component of the title of the sūtra is explained by Tao-sheng in terms of the proposition that the three unreal vehicles eventually give way to the real One Vehicle. Three of his four Dharma wheels are based on this idea.

How this theme is immersed in the individual chapters can be seen in the first paragraph of each chapter, which serves as its synopsis. Even earlier, however, we find in the beginning of Tao-sheng’s introductory chapter a tripartite breakdown of the sūtra according to this theme of three vehicles. In his analysis, the first thirteen chapters of the sūtra show that the cause of the three vehicles is really the cause of the One. The next eight chapters indicate that the effect of the three is to be identified with the effect of the One. The remaining six chapters are concerned with believers of the three in the process of becoming adherents of the One.