The diagonal line is a powerful visual element in interior composition, carrying kinetic energy distinct from the calm stability of horizontal lines and the structural firmness of vertical ones. It creates a sense of motion and direction within space, making it a strategic tool for guiding perception and organizing visual pathways. In contemporary interior design, diagonal lines activate walls and ceilings, adding dynamism and breaking the monotony of repetitive geometric forms. Visual perception studies show that diagonal lines attract attention faster because they are associated with motion and change. In commercial interiors, they enhance visual identity and capture user attention effectively. In residential spaces, diagonal lines are used carefully to avoid discomfort or instability. They may appear in wall treatments, lighting layouts, furniture design, or transitional elements like stairs, emphasizing upward or downward motion. Psychologically, diagonal lines evoke dynamic tension or positive energy, which must align with the function of the space. In educational environments, they can stimulate perception and engagement, while in therapeutic spaces their presence is minimized to maintain calmness. Diagonal lines also create extended visual perspective and guide spatial movement. They are fundamental in movements such as Deconstructivism, which redefined the relationship between mass and void. Technically, implementing diagonal elements requires precise measurements and thoughtful lighting design, since shadows can strengthen or weaken their visual impact. Combined with varied materials, suspended ceilings, or flooring patterns, diagonal lines can enhance depth and create a sense of spaciousness in compact interiors. However, excessive use may cause visual confusion or perceptual imbalance, so their application must be balanced aesthetically and functionally. Ultimately, the diagonal line is not merely a formal element but a perceptual tool that shapes user experience and contributes to contemporary spatial identity. Almustaqbal University, The First University in Iraq.
  الهدف الرابع (التعليم الجيد)