The order of the prayers is one of gradual ascent, rising ever higher among the 'Four Worlds,' from one sphere to the next - the higher - one: from
(a) Asiyah, the 'World of Action' of the Birchot Hashachar to
(b) Yetzirah, the 'World of Formation' of the Pesukei Dezimra, to
(c) Beri'ah, the 'World of Creation' of Birchot Keri'at Shema and the Shema, to
(d) Atzilut, the 'World of Emanation' of the Shemoneh Esrei.
The faculties of the animal soul relate to this material world.
Their sustenance is from the vital powers in the victuals which sustain the life of man's body and his animal soul, and which have the potential of being elevated to sanctity.
Man, therefore, is bound to 'below' (material reality). Thus he must elevate the soul and bind it unto G-d. He must conquer the sitra achara (the 'other side,' as opposed to the 'side of holiness') and turn it around to "serve Him with all your heart," i.e., with both your spiritual and physical inclinations, to the point of attaining Echad.
The essence of all prayer is the contemplation of Echad - that "G-d is Echad (One)" (Deuteronomy 6:4), the sole reality, even now after the creation of the universe in space and time. He is and remains Echad - east, west, north, south, above and below, and likewise in terms of time (past, present and future).
For relative to G-d it is all the same, the present status with that prior to creation, prior to the categories of time and space.
The gradual intensification of the order of prayers follows the pattern of the ladder that appeared in Jacob's dream, the four rungs of which one is to ascend.
Tefilah is the 'ladder set in the earth, and its top reaches into heaven.'
One begins all the way below: first the Birchot Hashachar, 'Blessed are You who opens the eyes of the blind.' One proceeds from the lowest level until literally reaching the state of "You shall love G-d" - i.e., submitting the soul at Echad.
The ladder of tefilah allows us to ascend. It is the intermediary "uniting the higher with the lower. The one above can descend on it to the one below, even as the one below can ascend on it to the one above."
Of this ladder it is said that "the messengers of G-d ascend and descend on it": by means of this ladder man elevates himself.
His mitzvot (which are referred to as 'messengers of G-d', the observance of which involves matter, ascend and rise upwards on this ladder. In turn, it is by means of this ladder that the Heavenly Grace is drawn forth and downwards.
Tefilah 'reaches into heaven' and establishes a zivug (union) with offspring of a completely new consciousness.
