"Gradually, Bonifacio gravitated more towards del Pilar for guidance. In fact, he solicited del Pilar’s approval for the by-laws of the Katipunan. Del Pilar wrote him a letter endorsing the secret society and this served as encouragement for an all-out recruitment campaign. The extent of del Pilar’s influence could be best gauged in terms of the impact of his letters on Deodato Arellano, a brother in law, who was a co-founder of the Katipunan. It was reported that Bonifacio copied these letters faithfully because he treasured them as valuable guides for action. Del Pilar served as Bonifacio’s mentor."