What kind of balance did edward weston use to create contrast in the photograph shell , 1927?

Edward Weston used the balance in difference in value to create contrast in the photograph 'shell',  taken in 1927. The shell was a medium sized black and white photograph image that featured a nautilus shell balanced within an abalone shell that rested on a semi-reflective surface. The shells are set against a plain, dark background with pale tones that shine against it thus showing the difference in value to create contrast.

i believe the answer is  the similarity is that both are sacrifices which have the same purpose and sacrifice - jesus christ, but the difference is in offering of that sacrifice.

the similarity is that both are sacrifices which have the same purpose (repenting our sins) and sacrifice - jesus christ.  the difference is in the way of the offering that sacrifice. the sacrifice of jesus on the calvary is sacrifice of his actual living body and blood, but the sacrifice of the mass is the sacrifice of the jesus through bread (body) and blood (wine). in the sacrifice on calvary jesus was offered for us; while at mass he offers himself through us.