Excerpts From Signless Buddha Mindfulness
Venerable Xiao Pingshi
Essentially, to “enter samādhi,” one needs to be able to not only “rein in all the six sense faculties” but also “abide in one continuous pure thought.” The fulfillment of these two conditions specifically points to a state free of any sign. Here’s a passage from the Jewel Heap Sutra that illustrates my point: “Signlessness refers to the absence of a body and its designation, the absence of words and letters, and the absence of appearances and manifestations.”
Abiding in one continuous pure thought connotes the thought that held in mind being a pure thought. Thoughts about worldly matters are not pure thoughts; even thoughts about virtuous acts or the Buddha Dharma are not considered pure. In terms of the cultivation of meditative concentration, any thoughts that come with language, symbols, or images are considered deluded and impure. The recollection and mindfulness of the Buddha can be deemed pure only if the thought of the Buddha is free of them. Only when one can bear such a pure thought of the Buddha in mind without interruption can one be considered “abiding in one continuous pure thought.”
Signless Buddha Mindfulness, Chinese version, p. 39-40