What can people understand more about what artist intended with a piece and what meaning it might have

What can help people understand more about what an artist intended with a piece and what meaning that piece might have is the context (both of creation and of reception). The context of creation is the setting - political, social, economic, cultural, religious, philosophical - in which a work of art was produced, and the context of reception refers to the original and the subsequent scenarios in which the work of art was exhibited, experienced, and appropriated. Since works of art are shaped by that context, they are a reflection of it, or they simply arise from it (as much as from the artist's genius and creativity), knowing more about it can truly help to better understand the original artistic intentions and meaning of specific works of art, particularly of those that were created hundreds of years ago, as well as the subsequent interpretations by later generations of viewers.  

whose power in the senate is equal to the power of the speaker of the house?

c. troops marched forward in close formation against newer, more accurate weapons