Sentence:  If any literary work is too long to be read at one sitting, we must be content to dispense with the immensely important effect derivable from <WSD>unity</WSD> of impression - for, if two sittings be required, the affairs of the world interfere, and everything like totality is at once destroyed. 
Meaning of the word marked with <WSD> tags:  Oneness; the state or fact of being one undivided entity.