* The power of nature. Steinbeck's novels often feature powerful natural forces, such as storms, floods, and droughts. These natural forces can be both destructive and life-giving, and they often play a significant role in the lives of Steinbeck's characters. In _Of Mice and Men_, for example, the Salinas Valley is a beautiful and fertile region, but it is also subject to periodic floods that can devastate the crops and threaten the lives of the people who live there.
* The struggle for social justice. Steinbeck's novels often address social issues, such as poverty, inequality, and discrimination. In _The Grapes of Wrath_, for example, the Joads are a family of poor farmers who are forced to migrate to California in search of work. They face discrimination and exploitation at every turn, and they eventually join a labor movement that is fighting for better wages and working conditions.
* The search for meaning in life. Steinbeck's novels often explore the search for meaning in life. In _East of Eden_, for example, the Trask family is a multi-generational family that struggles with sin, guilt, and redemption. The novel raises questions about the nature of good and evil, and it suggests that there is no easy answer to the question of what it means to be a good person.