http://www.scientificamerican.com/ar...SA_ENSTNCRBS_1
Brian Greene: "In March of that year he argued that light, long described as a wave, is actually composed of particles, called photons, an observation that launched quantum mechanics. (...) In June he completed the special theory of relativity, revealing that space and time behave in astonishing ways no one had ever anticipated--in short, that distances, speeds and durations are all relative depending on the observer."

That is, in June Einstein abandoned the particle concept of light (which provided the simplest and most natural explanation of the Michelson-Morley experiment) and took from the ether theory the continuous-field concept, with the central tenet that the speed of light is constant (independent of the speed of the light source):

http://books.google.com/books?id=JokgnS1JtmMC
Relativity and Its Roots, Banesh Hoffmann, p.92: "There are various remarks to be made about this second principle. For instance, if it is so obvious, how could it turn out to be part of a revolution - especially when the first principle is also a natural one? Moreover, if light consists of particles, as Einstein had suggested in his paper submitted just thirteen weeks before this one, the second principle seems absurd: A stone thrown from a speeding train can do far more damage than one thrown from a train at rest; the speed of the particle is not independent of the motion of the object emitting it. And if we take light to consist of particles and assume that these particles obey Newton's laws, they will conform to Newtonian relativity and thus automatically account for the null result of the Michelson-Morley experiment without recourse to contracting lengths, local time, or Lorentz transformations. Yet, as we have seen, Einstein resisted the temptation to account for the null result in terms of particles of light and simple, familiar Newtonian ideas, and introduced as his second postulate something that was more or less obvious when thought of in terms of waves in an ether. If it was so obvious, though, why did he need to state it as a principle? Because, having taken from the idea of light waves in the ether the one aspect that he needed, he declared early in his paper, to quote his own words, that "the introduction of a 'luminiferous ether' will prove to be superfluous."

http://www.worldscientific.com/world...s/10.1142/6019
Frank Wilczek, Fantastic Realities, p. 294: "One of the most basic results of special relativity, that the speed of light is a limiting velocity for the propagation of any physical influence, makes the field concept almost inevitable."

https://en.wikipedia.org/wiki/Lorentz_ether_theory
Albert Einstein: "...it is impossible to base a theory of the transformation laws of space and time on the principle of relativity alone. As we know, this is connected with the relativity of the concepts of "simultaneity" and "shape of moving bodies." To fill this gap, I introduced the principle of the constancy of the velocity of light, which I borrowed from H. A. Lorentz's theory of the stationary luminiferous ether..."

http://arxiv.org/ftp/physics/papers/0101/0101109.pdf
"The two first articles (January and March) establish clearly a discontinuous structure of matter and light. The standard look of Einstein's SR is, on the contrary, essentially based on the continuous conception of the field.."

http://www.pbs.org/wgbh/nova/einstein/genius/
"And then, in June, Einstein completes special relativity, which adds a twist to the story: Einstein's March paper treated light as particles, but special relativity sees light as a continuous field of waves."

At the end of his life Einstein was sorry for having adopted the field concept, that is, the false constant-speed-of-light tenet, but it was too late:

http://www.perimeterinstitute.ca/pdf...09145525ca.pdf
Albert Einstein (1954): "I consider it entirely possible that physics cannot be based upon the field concept, that is on continuous structures. Then nothing will remain of my whole castle in the air, including the theory of gravitation, but also nothing of the rest of contemporary physics."

Pentcho Valev