To me, the thinking process manifests itself in the language which we have learned as children.
For example, when we ponder a question or attempt to logically determine the validity of a conundrum, we do this cogitating in our native tongue within our consciousness. We don't speak the words, but we think them in the grammar with which we are familiar.
But, that aspect of thinking is only one small element. We also use visualization and all other senses to support the thinking process...