पातञ्जल योगसूत्र (स्वामी विवेकानन्द भाष्य एवं सूत्र व्याख्या)

Patanjali Yoga Sutras
The one-pointedness of the Chitta is when it grasps in
one, the past and present.
How are we to know that the mind has become concentrated?
Because time will vanish. The more time vanishes the more
concentrated we are. In common life we see that when were
are interested in a book we do not note the time at all, and
when we leave the book we are often surprised to find how
many hours have passed. All time will have the tendency to
come and stand in the one present. So the definition is given,
when the past and present come and stand in one, the more
concentrated the mind.
13. एतेन भूतेन्द्रियेषु धर्मलक्षणावस्थापरिणामा व्याख्याताः ॥ १३ ॥
etena bhootendriyeshu dharmalakshanavastha
parinama vyakhyatah
By this is explained the threefold transformations of
form, time and state, in fine or gross matter, and in the
organs.
By this the threefold changes in the mind-stuff as to form,
time, and state are explained. The mind-stuff is changing into
Vrttis, this is change as to form. To be able to hold the changes
to the present time is change as to time. To be able to make
the mind-stuff go to the past forms giving up the present even,
is change as to state. The concentrations taught in the
preceding aphorisms were to give the Yogi a voluntary control
over the transformations of his mind-stuff which alone will
enable him to make the Samyama before named.
103