The Hayward exhibition opened at the point (1948) when Rothko was still engaged in pulverizing recognizable objects. It was a weak starting point; the 1948 paintings are difficult to look at, indecisive and amorphous, and very much part of the conscious search for an alternative to semi-abstract Surrealism. It would have been wiser to have started earlier, or slightly later with the breakthrough to unequivocal abstraction. In the 1948 paintings Rothko experiments with many different colouristic and textural arrangements within each picture, thin paint against thick, luminous against dense, all with a very loose sense of how to use the boundaries of the canvas as a form of control. Rothko said of his paintings in 1947 that ‘they have no direct association with any particular visible experience, but in them one recognizes the principle and passion of organisms. One certainly does recognize this principle in them, and it is precisely the organisms’ independence of the artist's intelligence and will that mars their impact.

Recalling in these terms the magnificent No 20, 1950 (the earliest painting with a ‘typical’ format in the exhibition), one can see how Rothko resolved the threat of possible anarchy. It is still an organic painting, involving movement and development in detail, though a more controlled form than previously. There is also an authoritarian framework of rectangles against ground colour of the kind already described. The painting's dimension (116 x 102 inches, roughly twice the size of the earlier pictures) gives it a natural authority, as does its simplicity. The layout is easily understood, particularly the strongest colour, a band of crimson, divides the height of the canvas in the proportion of the golden section, and the basic colour design is straightforward: pink is introduced with increasing intensity into the blocks of white in the upper half of the picture as they descend towards the crimson, and below a rectangle of lime green rests on the overall yellow ground. Change of tone and colour, which in the earlier pictures had been sudden and unpredictable, here becomes gradual, so that emphasis is switched from novelty within the picture to continuity. The new control of gradation reduces a shout to a whisper, and when Rothko remarked that ‘silence is so accurate’, he pinpointed the new exactness that his painting acquired by the elimination of sudden contrasts and oppositions.

The colours of No 20, 1950 give it a steady, luminous quality. Not all the 1950s paintings in the Hayward had a comparably silent character. In White, Red on Yellow of 1958, another yellow-ground painting, Rothko chose a much harder and denser yellow, and arranged on it two blocks of colour, smaller than customary in proportion to the ground colour, and even more than usually symmetrical in their placing. The lower, red, block is uncharacteristically dense and flat, but the lack of activity within the colour is partly compensated for by the liberty with which the red brushmarks are allowed to spread over the yellow. By contrast, the higher, white, block is laid on very thinly over a brownish ground with brushmarks very much in evidence; but, unlike the red, the white is not allowed to spill over into the yellow. The painting is built out of contrasts, both of actual colour, and of the way the colours are handled.

In a sense this kind of treatment refers back to the sort of contrasts set up in the 1948 paintings, even if here they are carried out with much greater sureness. In the following ten years, to 1968, Rothko narrowed his field of activity, so that smaller nuances of colour and tone are loaded with greater meaning. Contrast is largely replaced as a principle by gradation.