How did Martin Buber respond to Franz Rosenzweig's criticism of I and Thou?

After reading Ich und Du (I and Thou), Franz Rosenzweig remarked to his friend Martin Buber that while Buber gave unprecedented recognition to the "Thou," he simultaneously "wrongs the 'It'."1

Many years later, Buber responded to this criticism by explaining that his focus was a deliberate reaction to the historical context of his time. He argued that had he lived in an era when the "Thou" was flourishing, he would have "sounded the praises of the It." However, because he lived in a time when the "Thou" was withering, he felt compelled to do the reverse to restore balance.1