Yoga Sutras 1.43
Patanjali, explained by Swami Vivekananda
स्मृतिपरिशुद्धौ स्वरूपशून्येवार्थमात्रनिर्भासा निर्वितर्का ॥
smṛtipariśuddhau svarūpaśūnyevārthamātranirbhāsā nirvitarkā
The Samadhi called "without question" (comes) when the memory is purified, or devoid of qualities, expressing only the meaning (of the meditated object).
In plain words: A higher meditation comes when memory is cleaned of labels and old associations. Then only the object itself shines in the mind. This is called samadhi "without question" (nirvitarka).
Swami Vivekananda explains
It is by the practice of meditation of these three that we come to the state where these three do not mix. We can get rid of them. We will first try to understand what these three are. Here is the Chitta; you will always
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remember the simile of the mind-stuff to a lake, and the vibration, the word, the sound, like a pulsation coming over it. You have that calm lake in you, and I pronounce a word, "Cow". As soon as it enters through your ears there is a wave produced in your Chitta along with it. So that wave represents the idea of the cow, the form or the meaning as we call it. The apparent cow that you know is really the wave in the mind-stuff that comes as a reaction to the internal and external sound vibrations. With the sound, the wave dies away; it can never exist without a word. You may ask how it is, when we only think of the cow, and do not hear a sound. You make that sound yourself. You are saying "cow" faintly in your mind, and with that comes a wave. There cannot be any wave without this impulse of sound; and when it is not from outside, it is from inside, and when the sound dies, the wave dies. What remains? The result of the reaction, and that is knowledge. These three are so closely combined in our mind that we cannot separate them. When the sound comes, the senses vibrate, and the wave rises in reaction; they follow so closely upon one another that there is no discerning one from the other. When this meditation has been practised for a long time, memory, the receptacle of all impressions, becomes purified, and we are able clearly to distinguish them from one another. This is called Nirvitarka, concentration without question.