The overall meaning of the poem is that there is a natural end to all human endeavors.  This natural end could be death, or it could simply be the termination point for all that is done.  Shakespeare employs several ways to accomplish this.  The repetition of the verse "come to dust" which closes each of the three stanzas accomplish this.  The first stanza's use of summer and winter seasons also bring the idea of a cycle of life, death, and rebirth to mind.  Additionally, in line 9, the idea of "care no more to clothe and to eat," brings to mind that all human activity, while we consider it important, does not necessarily evade the fact that there is a natural end to everything we do.  The rhythm of the poem is established with  a couplet at the start and and end of each stanza, beginning with "Fear no more" and ending with "comes to dust."  The tone of the poem strikes with a resigned melancholy.  The speaker does not seem overwhelmingly sad or angry with the natural end of everything "coming to dust."  Yet, there is a silent acceptance over the fact that death ends everything.  There is a tinge of sadness, but it is not overwhelming throughout the poem.  Through the use of specific images, both human made (line 9) and pictures of natural phenomena (lines 13 and 14, thunder and lightning), Shakespeare creates the meaning that everything faces a natural end.