What is Kipling's purpose for beginning several lines in each stanza with the word "if", in the poem "If"? To create rhythm or repetition?

The developments of literary theory since the 1960s have
stressed the impossibility of knowing the authors' real purposes when they compose a
literary work. What we can say is that, whatever Kipling's purposes, the repetition of
the word IF at the beginning of a line (a figure of speech called "anaphora") creates
rhythm in the poem. In his Linguistic Guide to English Poetry
Geoffrey Leech links repetitions and verbal parallelism to music. It is also
useful to note that repetitions/verbal parallelisms are different from mere duplication.
In Kipling's lines there is an element of sameness ("If you can. . .") and an element of
variation (the other part of the line). In addition to the creation of rhtyhm, the
repetition of the word IF gives the poem a didactic tone which conveys to its readers
the meaning of true adulthood.