Some Cayce quotes to get you started:
Again, in the figurative sense, we find that light and darkness, day and night, are represented by that termed as periods of growth and the periods of rest or recuperation, through the activities of other influences in those forces or sources of activity condensed in form to be called matter, no matter what plane this may be acting from or upon. (262-55)
(Q): Is it true that day and night are condensed or miniature copies of incarnations into the earth and into planetary or spiritual sojourns; they in turn being miniature copies of what took place in the Beginning?
(A) Very good, if you understood just what all this means! It's a very good illustration of that which has just been given; as to how there is the evolution of the soul, evolution of the mind, but not evolution of matter - save through mind, and that which builds same....
(Q): May I have a message on Day and Night that will help me in my contribution to the lesson?
(A) THINK on the experiences of self, as self has passed from darkness unto light, from day unto night, in the MENTAL associations of that which makes the awareness of that which would make of thee a channel of blessings to many. And then there may be seen in self's experience the meaning of what is Day, and what is Night. The ability to become aware; or, to put into other words, to become CONSCIOUS is Day and Night. (262-56)
(Q) When will this trouble clear up?
(A) When will it rain! When there are those things necessary for the awakening in the physical functioning of a body to produce constructive rather than destructive forces, a body may be said to be wholly on the improve - and the disorders being eliminated. When there are the applications that insure such conditions, THEN these may be expected as a result. Causes and effects are EVIDENT in a material world. While one follows the other, they are as interlocking as day and night. When does night begin, or when does day begin? They are ONE and the same, RELATIVELY. Time, space - as set by man, as relative to any physical condition, as to WHEN it may be: When he has complied with the laws that govern the physical, the mental, the material things - then the change begins. (343-2)
How ORDERLY is there brought into manifestation day and night, heat and cold, spring and summer! And when nature (as man Calls God) in its awakening begins, how orderly are the manifestations led! thou in thine tenseness seeing not the growth of the lily nor the rose, nor understandest thou the bird upon the wing, nor seest thou not the germ in the seed nor the bulb; yet ALL are ORDERLY, decently, in their place. (440-14)