In "Tradition and Individual Talent" T. S. Eliot talks about present time as an embodiment of past time; this he calls "tradition" ans ties talent as a poet to knowing and manifesting the greatness of the past in the poetry of the present.
In Four Quartets, Eliot describes his life in England and America, expressing the concept that in the moments of being in one location, he is also embodying the moments of the other location; this describes a cycle of place. He illustrates it by describing his experience pertaining to two places in America and saying that when he is in New England, he misses the "long dark river,...the flaming cardinal birds" of Missouri but, when in Missouri, he misses the "firs trees,...the song sparrow,...and the blue sea" of New England.
Eliot's concept of circular journeys is that time and place are a "migration" (Four Quartets) that rounds back on itself. Picture a scenic route train that leaves the station and goes up the hill, rounds it, and comes down the other side reentering the station from a different route, place and direction. Eliot held that time, past and present, is images to be explored until, like the scenic train, we are led back to the present--from which the journey started--thus showing the circular journey that man takes. In other words, a circular journey is that which starts with self in present day and present location then explores the images of prior times and places--always carrying the present along in psyche, thought and feeling--until the exploration leads through circularity back to the present.
[For more information, see A Reader's Guide to T. S. Eliot: A Poem-by-Poem Analysis by George Williamson.]