Rabbi Morris Lichtenstein wrote: “Faith is the infinite in man reaching out to join its Source.” 
I confess that this puzzled me for a long time. The “infinite,” by definition, has no source.
But after writing the previous post on ibn Gabirol’s poem, I think that I came to understand what Rabbi Lichtenstein meant, especially as it relates to prayer.
We often hear people write and talk about praying from the “head” or the “heart.”
To say only the words of prayer, without a personal concern for what we’re saying, would be one kind of “head-prayer.” It’s the way schoolchildren recite “The Pledge of Allegiance.” Another would be an advanced understanding of the meaning of the prayers without being touched by them personally. Even great knowledge of the comments and commentaries of the holiest interpreters is just saying someone else’s “words” until our hearts are moved.
Praying “from the heart,” then, is praying as if the words of the prayers are our very own.
When I was a congregational cantor many years ago, a congregant asked me why the prayers were so pre-determined. In answering, I compared the siddur to a script that an actor or actress uses in a play or film. The words are set, but the proper performance of them requires personal inspiration. To be inspired in that way, the prayers must have a personal meaning. This doesn’t negate learning. Much the opposite. When the prayers have personal meaning, the words of great interpreters open up wider realms of personal relevance to us.
It’s further true that when we pray in this personal way, we’re no longer praying with the “head” alone. If we’re worried and say “G-d is my help” in a personal, affirmative way, our worry will dissolve.
It need hardly be said that this discussion isn’t confined to liturgical prayer — the formal prayers that are said in synagogue. The points are just as relevant to the personal prayers we might say ourselves — any time, anywhere. This is especially true of the “affirmative” and “visualized” prayer that Rabbi and Mrs. Lichtenstein taught.
When we pray in a personal way, we’re praying with — from — a deeper part of ourselves. The deepest part of us is the Divine soul in us. Ibn Gabirol calls it the “nishmat El-ha” — the “Divine soul” or “Divine breath” (after the “nishmat chayyim” that G-d breathes into Adam). It’s the essence of who and what we are. It’s the “infinite” in us. Rabbi Lichtenstein is saying, then, that real prayer is prayer from the truest part of who and what we are.
One might even paraphrase Rabbi Lichtenstein: Real prayer (or real faith) is the infinite in man recognizing that it is eternally joined to, and identical with, it’s Source.
When the infinite in us recognizes its Source, we experience G-d, or G-d’s Presence.
Mrs. Lichtenstein later described this, too:
“…G-d cannot be perceived through the mind [i.e. intellect] alone. If you would know G-d, do not seek merely to prove His existence, but turn to Him with your heart; affirm your union with Him, affirm His responsiveness to prayer, pray to Him; if you actually turn to G-d … speak to Him in your heart, you will be astonished to find how close He is to you, you will feel His nearness, you will have found G-d.” 
The “joining” is permanent. The recognition remains intermittent until we reach a spiritual level at which even the recognition, or perception, is also permanent. Then, “faith” and “prayer” become indistinguishable from each other.
Experience bears it out.
 Lichtenstein, Rabbi Morris; Jewish Science and Health; p. 136
 Lichtenstein, Tehillah; Applied Judaism; Doris Freedman, ed.; “Can We Prove That G-d Exists?”; p. 96;
(originally part of “How Shall We Find G-d;” Jewish Science Interpreter; June, 1940; p. 4)