Oil painting is an expressive art form that allows artists to express emotions and the inner world through elements such as color, line, composition, and theme. Different artists and works can convey a wide range of emotions and ideas, Here are some common ways:

1. Color: Color is a very important element in oil painting. Bright tones can convey joy, excitement, or energy, while darker tones may express depression, worry, or contemplation. For example, the bright colors in Van Gogh's "Starry Night" convey his inner passion and excitement.

2. Brushstrokes and Texture: Artists can express emotions through different brushstrokes and textures. Rough brushstrokes and traces of oil paint left by the artist may express restlessness or impulsiveness, while smooth brushstrokes and delicate painting techniques may convey inner peace and calm.

3. Theme and composition: The theme and composition of an oil painting can also reflect the artist's inner world. For example, abstract art may express complex emotions and ideas through unconventional compositions and shapes, while realistic oil paintings may convey emotions through concrete themes and details.

4. Symbols and Symbols: Some oil paintings use symbols and symbols to convey emotions. For example, a withered flower could represent the fragility of life, and a flying bird might symbolize freedom or hope.

5. Subjectivity: Art is subjective, and each viewer may feel different emotions and inner experiences from the same oil painting. This depends on the viewer's personal background, emotional state, and interpretive abilities.

6. Time and historical background: Oil paintings can reflect emotions and thoughts in a specific period and historical background.

7. Art Movements and Styles: Different art movements and styles can express unique emotions and inner experiences through oil painting. For example, Expressionism emphasizes emotion and inner conflict, while Surrealism expresses dreams and fantasies through unrealistic scenes and images. An artist's choice of a specific style can influence the way they express their emotions.

8. Artists’ life experiences: Artists’ life experiences and personal stories are often reflected in their works. Painting can be an artist's way of dealing with personal challenges, growth, and change, and as a result, the work may convey the artist's emotional experiences in life.

9. The social and cultural role of art: Oil painting is not just a way for individuals to express their emotions, but it can also play a role on a social and cultural level.

It can convey universal emotions and themes, resonate with the audience, and prompt them to think about social, cultural, and human issues.

10. The therapeutic and expressive functions of art: For some artists and viewers, oil painting is a way to heal and express emotions. By creating or appreciating oil paintings, people can express, explore, and understand their emotions and inner experiences, which helps to vent their emotions and inspire them.

In short, oil painting is a multi-layered art form that can express emotions and the inner world through multiple elements and levels. Each oil painting is an emotional and ideological bridge between the artist and the audience and can trigger profound discussions and resonance in different cultural and social backgrounds.