Yoga Sutras 3.3

Patanjali, explained by Swami Vivekananda

तदेवार्थमात्रनिर्भासं स्वरूपशून्यमिव समाधिः ॥

tadevārthamātranirbhāsaṃ svarūpaśūnyamiva samādhiḥ

When that, giving up all forms, reflects only the meaning, it is Samādhi.

In plain words: Samadhi, a state of deep absorption, comes when meditation lets go of the object's outer form. Only its meaning shines in the mind.

Yoga Sutras 3.3

Ask the Swami about this

Swami Vivekananda explains

That comes when in meditation the form or the external part is given up. Suppose I were meditating on a book, and that I have gradually succeeded in concentrating the mind on it, and perceiving only the internal sensations, the meaning, unexpressed in any form — that state of Dhyana is called Samadhi.