In the Gleanings, Baha'u'llah writes that we should speak of His Revelation in a manner that causes a tumult in the hearts of the people:
Proclaim, then, that which the Most Great Spirit will inspire thee to utter in the service of the Cause of thy Lord, that thou mayest stir up the souls of all men
This section CXXXIX of the Gleanings is from a Tablet addressed to Nabil-i-Azam, the author of Nabil's Narrative, the Dawn-breakers. Here is an example of how Nabil followed Baha'u'llah's admonition to stir up the souls of men: Nabil raised up Badi and prepared him to meet Baha'u'llah and give his life for the Cause.
The Hand of the Cause Hasan Balyuzi explains that during a visit to a believer's home, Nabil found the father of Badi taking care of everything. Nabil asked the man, did he not have a son? The man answered that his son, known then as Aqa Buzurg, was unruly and was not interested in his father's doings, and was the despair of his family. Nabil writes that he said to the father:
"Send for him to come, I wish to see him." He was sent for and he came. I saw a tall, gangling youth, who, instead of physical perfections, had merely a simple heart, and I told his father to make him my host and leave his case to God . . . Then, I mentioned matters, very moving, which would melt a heart of stone.' Nabil-i-A'zam here quotes a number of verses from the long poem by Bahá'u'lláh - Qasidiy-i-'Izz-i-Varqa'iyyih, which he composed in Sulaymaniyyih. In these verses quoted by Nabil, Bahá'u'lláh speaks of His own sufferings and tribulations.
'Hearing these divine themes, the colour of the visage of that youth reddened. his eves welled with tears, and the sound of his lamentation rose high. I calmed his agitation, but throughout that night, his enamourment and attraction kept sleep away from the eyes of Shaykh Muhammad and myself. Until the light broke we read and recited from the holy script. In the morning, when he prepared the samovar for tea, and went out to fetch milk, his father came and said: "I had never heard my son weep. I thought that nothing could move him. Now, what is the spell cast on him to make his tears flow and to cause him to cry out, to make him afire with the love of God?" I said: "In any case he is no longer in command of himself, and you must give him up." And his father said: "This manner of losing one's self is exactly what I desired. If he remains firm in the Cause of God, I myself shall serve him."
(Balyuzi, Baha'u'llah - The King of Glory, p. 294)
Baha'u'llah then recreated Aqa Buzurg and gave him the name Badi' -- which means new, unique, wondrous, unprecedented. Perhaps we can keep Baha'u'llah's admonition and Nabil's example in mind, when we follow the guidance of the Universal House of Justice to teach the heart:
"The friends must teach with conviction, determination, genuine love, lack of prejudice, and in a simple language addressed to the heart."
(The Universal House of Justice, Messages 1963 to 1986, paragraph 18.18, p. 41)