Dharana, dhyana, and samadhi
The third chapter of the Yoga Sutras begins with three definitions. Iyengar reads them as related changes in attention. It stays with an object, becomes continuous, and eventually the object takes center stage in the experience.
Dharana and a chosen focus
Sutra III.1 describes dharana as holding chitta in a chosen area. Choosing an object and remaining with it are distinct actions. The choice may be immediate. Holding attention involves staying with the object as other impressions arise. Iyengar treats deliberate attention as a basis for the practice that follows.
Dhyana and continuity
Sutra III.2 describes continuity of attention toward the same object. Iyengar connects dhyana with a change in the quality of this process. In dharana, the effort to hold attention is still noticeable. The description of dhyana emphasizes the continuity of attention itself.
Samadhi and samyama
In sutra III.3, the object stands out so fully that the perceiver’s own form seems to recede. Iyengar describes this as absorption and considers several forms of samadhi. Sutra III.4 calls the three together samyama when they concern the same object.
What it means to have the same object
The definition of samyama depends on a detail that is easy to pass over. Dharana, dhyana, and samadhi concern one and the same object. Patanjali is describing how the relationship to that object changes. To see why the detail matters, imagine starting with the feel of a hand resting on a surface and then following a noise. Both can be experienced clearly, but the object has changed. This illustrates why continuity involves the direction of attention as well as the time spent attending.
Where effort is noticeable
The distinction between choosing an object and staying with it becomes clearer when the effort of staying is easy to feel. Suppose you decide to examine a detail in a painting. You may return to it repeatedly because other details draw the eye. At another moment, that same detail may hold your attention with less noticeable intervention. Looking at a painting serves as an illustration of changing effort. Iyengar’s terms refer to the particular inward practices described by Patanjali.
How far the comparison extends
Patanjali calls these three limbs inward in relation to the preceding five. He then makes a further distinction by calling them outward relative to seedless samadhi. Iyengar takes up this contrast when he discusses forms of absorption with and without a seed. The relation matters because the same word, samadhi, appears in discussions at different depths of practice. Reading the definitions in sequence helps make sense of how the text can describe an experience of absorption and still go on to examine its limits.
Reading the definitions together
Ask where attention is directed, whether it remains continuous, and how the relationship between the object and the perceiver changes. The three questions distinguish the qualities Patanjali is describing.
Source
B. K. S. Iyengar. Heart of the Yoga Sutras.