Tears welled up in my eyes as I stared at the lifeless bodies of the mice lying before me. Their tiny chests no longer rose and fell with breath, their once lively whiskers now still. Guilt weighed heavy on my heart as I realized what I had done. I had used chloroform to kill them, a necessary step in my research, but one that left me feeling regret. The sacrifice of these innocent creatures made me feel upset, even as I knew it was for the greater scientific good. For knowledge it felt like a heavy burden as my eyes swelled up to kill it.