A theme is not simply a topic that a poet chooses to write about. A theme also includes what a poet thinks or feels about the subject. Poetry themes are as varied as the experiences that make up human life. Themes like life and death, love, loneliness and nature occur often in poetry; however, there is no limitation on what is an appropriate subject for a poem.
Love and Nature
Whether a poet is currently in love with someone or has lost her love, the simple act of loving occurs again and again in poetry. Another common theme is nature, which includes what the poet thinks or feels about experiencing the natural environment or about surviving a natural disaster. How a poet feels about important life events such as illness, loneliness or grieving the death of a loved one arises often as a theme in poetry.
Celebrations and Devotion
A poet's insights about the experience of a holiday or celebration are conventional themes found in poetry. Holiday-themed poetry often appears in greeting cards or might be written in advance of the event as a gift. Poetry with a devotional theme revolves around a poet's experience with the divine and can also appear in the form of a prayer. Mythology is yet another theme found in conventional poetry. The journey of a hero on an adventure is the major theme in epic poetry.
Since some themes show up so often, common themes can become a cliche. The purpose of a poem is to share an extraordinary insight the poet has. This aim will not be accomplished, however, if a reader has heard a love poem or a lament so many times that the idea of reading another one drives him away. The way to avoid cliche in poetry is to write concretely from an unusual perspective that jolts the reader into reading the poem to the end.
Unconventional themes can provide a relief from over-used subject matter. Poems describing states of consciousness and politics occur with less frequency and offer a challenge to the poet to avoid abstract language, which can make a poem banal. Poems describing the horrors of war and the effect it has on people and the landscape is a less familiar theme in poetry. Another unconventional theme in poetry is curiosity about the future.