Other similes are also found in later stanzas of the poem. In stanza 6, Donne tells his love that their two souls have become one and says that their love will expand "Like gold to airy thinness beat". He is saying that death will not separate the two of them but will only make their love greater. A nugget of gold can be pounded into a sheet because it is flexible; their love is also flexible and will grow greater.
In stanza 7, Donne contradicts what he says in stanza 6, saying their two souls may not be one, but even if they aren't, they are like the feet of a compass. He extends this simile to the end of the poem. He is referring to the type of compass where the two parts are joined together at the top. You have probably used this type of compass in your math classes to draw circles. One foot doesn't move unless the other moves. His lover is the "fix'd foot", and he is the other. After death, their two souls will still be spiritually connected.
The first two stanzas form a simile developing the following idea: Let us part the way virtuous persons die—quietly and easily. The exaggerated phrases “tear-floods” and “sigh-tempests” are designed to tease the listener out of weeping, and then to emphasize the remaining parts of the poem, which are quite serious. The simile of dying men sets a serious tone and makes clear that the parting is genuinely painful, both for speaker and listener. The use of similes is simple and direct. This will set up the use of more complicated figurative language in the later stanzas and not have the reader lose their train of thought.