Leo Steinberg, one of the most brilliant, influential and controversial art historians of the last half of the 20th century, died Sunday at his home in Manhattan. He was 90.

His death was confirmed by his assistant, Sheila Schwartz.

Steinberg was an inspirational lecturer, a writer of striking eloquence and an adventurous scholar and critic who loved to challenge the art world’s reigning orthodoxies. Although trained in the study of the Renaissance and Baroque eras, he wrote as insightfully about modern art as he did about the old masters.

The titles of his two best-known books, “Other Criteria: Confrontations With Twentieth-Century Art” (1972) and “The Sexuality of Christ in Renaissance Art and in Modern Oblivion” (1983), suggest the range of his interests. The earlier volume, a collection of essays written between 1953 and 1971, includes extended meditations on Picasso and Jasper Johns as well as shorter reviews of artists like Willem De Kooning, Philip Guston and Raoul Hague that he wrote during a brief stint in the mid-1950s as a regular critic for Arts Magazine.

In “Other Criteria,” he laid out his philosophical terms. In the essay “The Eye Is a Part of the Mind,” first published in 1953, and in the title essay, from 1971, Steinberg spoke out against formalism, then the dominant approach to art analysis, with its view that a work’s artistic value lies not in its content but in its shape, line, color and other visual elements.

“Even nonobjective art continues to pursue art’s social role of fixating thought in aesthetic form, pinning down the most ethereal conceptions of the age in vital designs,” he wrote in “The Eye Is a Part of the Mind.”

In “Other Criteria” he declared, “Considerations of ‘human interest’ belong in the criticism of modernist art not because we are incurably sentimental about humanity, but because it is art we are talking about.”

Such arguments helped liberate a whole generation from the restrictive laws of formalist aesthetics, opening the field to more wide-ranging ways of studying meaning and representation in art.

Steinberg did not simply substitute interpretation of content for analysis of form. Rather, it was his ability to show how form and content are intertwined that made his writing so revelatory.

His ability to discover ever deeper and more interconnected levels of meaning in the form and imagery of an artwork gave his writing a narrative excitement, like that of a detective story.

But it also exposed him to accusations of overinterpretation by his more circumspect colleagues. In his review of Steinberg’s book “Michelangelo’s Last Paintings” (1975), eminent art historian E.H. Gombrich warned against Steinberg’s tendency to speculate on supposedly unprovable meanings.