Vessels

vessel, n.:

• a hollow container, especially one used to hold liquid, such as a bowl or cask.
• a person, especially regarded as holding or embodying a particular quality.

(OxfordDictionaries.com)

Scott Braun, my teacher at the Yale Summer Session,  gave an assignment to represent five vessels.  We were encouraged to make representations that went beyond the basic definition of a vessel as a physical container.  They conceptually represented what the vessels were for.  
Three of my "vessels":

The candles and mirror as vessels for light, reflection, movement, time, destruction, ritual, emotion, heat etc.
I lit the candles during class.  The time, process, and transience were as much a part of the sculpture as the physical materials.

The egg as a vessel for life, fragility, nurture, sustenance, protection, bird etc.

The terrarium as vessel for plants, earth, water, air, growth, life, death, insects, light, change etc.