The Dynamic Equilibrium of Interlinear Spacing
Conventional typographic wisdom frequently prescribes a line-height multiplier of approximately 1.5 as the universal foundation for optimal textual legibility.
While this prescription contains a kernel of validity, the nuanced determination of appropriate interlinear spacing transcends such reductive formulations, demanding contextual calibration across diverse typographic scenarios rather than blind adherence to a monolithic value.
The Horizontal-Vertical Relationship
The fundamental purpose of interlinear spacing lies in facilitating effortless visual navigation between successive lines of text during the reading process. Consider instances where your perceptual apparatus has inadvertently revisited previously consumed text or entirely bypassed content—such perceptual disruptions frequently indicate insufficient vertical separation between adjacent lines.
When typographic elements exist in excessive proximity along the vertical axis, readers completing a textual line at the terminal right margin face a treacherous visual journey back to the left margin, often encountering perceptual ambiguity regarding the appropriate entry point for continued reading.
This navigational challenge intensifies proportionally with increased line length. As the horizontal distance traversed by ocular saccades expands, the probability of perceptual disorientation during line transitions escalates correspondingly.
Consequently, interlinear spacing and textual measure must maintain a proportional relationship—constrained horizontal dimensions permit more modest vertical separation (approximately 1.5), while expansive textual measures necessitate amplified interlinear spacing (potentially approaching or exceeding a factor of 2).