In the first aliyah (section) of Parshas Vayikra, Hashem calls Moshe to come to speak with Him. It is not possible even for Moshe to encounter the presence of Hashem without being called. Hashem instructs Moshe about the korbanos, providing a way for Bnei Yisroel to come close as well. When a person brings up a korban, they are distancing themselves from the animalistic part of their nature, showing Hashem that they want to come close to Him. When we emphasize the tzelem Elokim (part of the Divine) within us, we can come closer to Hashem, even without being called like Moshe.