A person’s Hebrew name is their life-force, and therefore has a tremendous impact on that person. The Kabbalists explain2 that when a child is born, a kind of spirit of prophecy rests on the parents, giving them foresight into what name they should give their child. This is because a name is intrinsically connected with the essence of the child, and is a critical component of the person’s makeup.
(11) The angel of the LORD said to her further,
“Behold, you are with child
And shall bear a son;
You shall call him Ishmael,
For the LORD has paid heed to your suffering. (12) He shall be a wild ass of a man;
His hand against everyone,
And everyone’s hand against him;
He shall dwell alongside of all his kinsmen.” (13) And she called the LORD who spoke to her, “You Are El-roi,” by which she meant, “Have I not gone on seeing after He saw me!”-d
(15) And God said to Abraham, “As for your wife Sarai, you shall not call her Sarai, but her name shall be Sarah. (16) I will bless her; indeed, I will give you a son by her. I will bless her so that she shall give rise to nations; rulers of peoples shall issue from her.” (17) Abraham threw himself on his face and laughed, as he said to himself, “Can a child be born to a man a hundred years old, or can Sarah bear a child at ninety?” (18) And Abraham said to God, “O that Ishmael might live by Your favor!” (19) God said, “Nevertheless, Sarah your wife shall bear you a son, and you shall name him Isaac; and I will maintain My covenant with him as an everlasting covenant for his offspring to come.
“Who would have said to Abraham
That Sarah would suckle children!
Yet I have borne a son in his old age.”
(8) We merit this through Torah study. This is because the Torah is the Name of God, and the name of a thing is its vessel; within this name is contained the life force of that thing. As it is written, “living soul that is its name” (Genesis 2:19)—contained in the name of each thing is its soul and life force. This is why when we call a person by his name, we gain his attention immediately, because his total soul and life force are contained within his name.
R. Meir said: For every good deed a man performs, an angel is assigned to watch over him. If he does one good deed, one angel is assigned to him, and if he performs many good deeds, many angels are assigned to him, as it is said: For he will give His angels charge over you (Ps. 91:11). Every time a person increases the number of good deeds they performs,they adds to their good name. You find that a person is known by three names: the name by which their parents call them, the name by which other people call them, and the one they earn for themselves; the most important name is the name one earns for oneself.
And Rabbi Yitzḥak said: A person’s sentence is torn up on account of four types of actions. These are: Giving charity, crying out in prayer, a change of one’s name, and a change of one’s deeds for the better...a change of one’s name, as it is written: “As for Sarai your wife, you shall not call her name Sarai, but Sarah shall her name be” (Genesis 17:15), and it is written there: “And I will bless her, and I will also give you a son from her” (Genesis 17:16);

