As the Jewish people gathered at the foot of Mount Sinai, they heard the voice of G‑d speaking the Ten Commandments. The Torah describes the awesome experience:

And all the people saw the voices and the torches, the sound of the shofar, and the smoking mountain, and the people saw and trembled; so they stood from afar.

What is the meaning of the words “and all the people saw the voices”? How can voices be seen? The Midrash tells us that there is a disagreement regarding this verse. Rabbi Yishmael believes that the Jews did not see anything unusual. They saw the torches and heard the voices (in which case the word “saw” refers to the torches.) Rabbi Akiva, however, insists that the verse must be read literally—they actually saw the voices. In the words of Rabbi Akiva: “They saw that which is usually heard, and they heard that which is usually seen.”

According to Rabbi Akiva, the experience at Sinai was much more than just receiving ten moral instructions for life. Sinai was a spiritual revelation that changed the way the Jews perceived the meaning of existence. In general, the world can be divided into that which is “seen” and that which is “heard.” The concrete, physical needs, desires and experiences are “seen”; they are experienced as the ultimate reality. That which is abstract, theoretical and spiritual is “heard.” The intangible spirit is not something we can see with our naked eye. To experience it, we need to “hear” and “listen.” We must use our mind to discover truths that are not obvious to the observer.

According to Rabbi Akiva, at Sinai they “heard that which is usually seen.” In other words, the physical matter, which is usually perceived as absolute reality, became an abstract idea, while spirituality, “that which is usually heard”, became real and obvious.

The experience of Sinai was not merely a one-time event. Every time we study Torah, we are recreating the revelation of Sinai. We are not only hearing the words of G‑d being spoken directly to us, but our perception of what is meaningful and worthy is enhanced. When we study Torah, our priorities are realigned. The sublime ideas in life—meaning, holiness, transcendence—become real and tangible. For each time we study Torah, we are standing at Sinai and “seeing the sounds.”1

As taken from, https://www.chabad.org/tools/subscribe/email/view_cdo/i/8A35D917402345A2:48CBD0CC6924F227283A4091431088341DE118ADD02CC9A06CE07CBB944AB561#utm_medium=email&utm_source=6_essay_en&utm_campaign=en&utm_content=header