Engagement in any part of the Torah draws unto oneself the Divine splendor.
This brings us to the question of quantity–of observing anyone part against observing the whole, and the problem of doing a kindness as opposed to studying Torah.
One person will maintain that he can do no more than devote himself to intellectual pursuits of Torah.
Another is busy with good deeds.
To this the Talmud answers that for such persons, it would be better had they not been born, because any separation of a single mitzvah from the totality of Divine worship separates it from holiness and causes a cleavage in the person.
An act of sanctity is meaningful only within a framework that is holy.
When one is so wholly occupied with one thing that one criminally neglects another, one is losing touch with the essential, and that which occupies one becomes an intellectual game.
There is a story told in the Jerusalem Talmud of Rabbi Avihu, who lived in Caesarea and had sent his son to study in Tiberias with the great teachers.
Upon meeting someone from Tiberias, Rabbi Avihu asked what his son was doing.
The other told him that the young man was occupied with deeds of kindness, especially with burying the dead.
Rabbi Avihu said that this was indeed a great mitzvah for which few volunteered.
But when he came home, he wrote a letter to his son saying: “Are there not enough dead in Caesarea that I sent you to Tiberias?"
The point here is that when there are others who can perform a necessary task, one is free of the obligation to perform it.
On the other hand, there is another Talmud passage that lists the priorities of mitzvot, those which can be abrogated in the urgency of another:
Work is abrogated before Talmud Torah, Talmud Torah before burying the dead, and so forth.
Certain mitzvot take precedence or are considered more important than others.
The essential point is that, although every mitzvah is its own joy, the study of Torah is that special joy of direct contact, the relationship of union with the Divine.
True, every mitzvah contains the possibility of such union with God; as it was said, when a person gives charity, he is acting as the hand of God.
And this goes beyond the joys of contemplation and meditation.
But Torah is a level of joy that is more open and vulnerable to the soul.
When one is occupied with Torah, one is calling upon God, even though there is no apparent emotional involvement.
It is more like a spontaneous exclamation, unconsidered and genuine, and a true expression of something with which a person may not even be totally identified, but which exists, nonetheless, in his essence.
It is like crying out, "Father, father!" or like the saying, "All ye who are thirsty, come and drink!" and there is no water but Torah.
The thirst is the thirst for God, and only Torah will quench it.
It is like saying I do not desire a great abundance of experience, but I desire to come closer to the source, and for that I need to get to water.
What is being expressed here is the idea that the Torah is not an intellectual exercise.
It is the word of God, and it is the way to approach Him.
–Rabbi Adin Steinsaltz
From "On the Essence of Torah Study" in The Long Shorter Way by Rabbi Adin Steinsaltz