Both of Elizabeth Bishop's poems "Sestina" and "One Art" contain the theme of loss.
First, to examine "One Art," the theme of loss is defined in the first line:
The art of losing isn't hard to master.
Not only does the first line speak to learning to live with loss, Bishop goes on throughout the poem explaining different losses. Embedded throughout the poem are references to different losses: door keys, time, places, names, a watch, and homes.
In the poem, Bishop is simply stating that one loses many things throughout life and, based upon this, one can only master the "art of losing."
In "Sestina," the theme of loss is more deeply embedded indirectly. One must look for things which are lost although they are not necessarily stated as lost.
The rain mentioned in the first line could refer to the fact that the clouds have lost their rain. No longer is the rain a part of the cloud once it has fallen to the earth.
In line two, "failing light" is mentioned. This illustrates the fact that the day is coming to a close and that the day has been lost.
One last reference to loss appears when tears are mentioned. Tears can be regarded as falling because of a loss which one must face. The tears, once they fall, have been lost to the person crying.
Overall, sometimes loss is very defined (as in "One Art"). Other times, a reader must look for ways to justify a theme embedded within a text.