Straight lines: Straight lines suggest rigidity and precision. They are positive, direct, tense, stiff, uncompromising, harsh, hard and unyielding. They express force and strength. Straight lines(fig.3.1) have direction. The four primary directions are horizontal (H), vertical (V), left oblique (L) and right oblique (R). Adjacent directions such as V and VR or H and HL are similar or harmonious. Directions at right-angles to each other such as H and V or LV and RH are complementary.
Curved lines: Curved lines have flowing continuity. The slightly curved or undulating line is loose and flexible, because of harmonic transition in the change of direction. It’s slow, lazy movement is passive, gentle, feminine and soft. But the excessive use of this line creates an aimless, vague or wandering effect. The very actively curved line changes direction rapidly and produces active and forceful curve which gives feeling of restlessness and agitation. Moderately curved lines on the other hand are more restful, suggesting gracefulness and lyricism. The continuous progression of the spiral line suggests infinity.
The diagram below (Fig.3.2) shows the progression of lines from straight to curve.
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