Discourse on
Definition 1 of 1
Pro Tip 1/3Topic Specific
Use 'discourse on' when focusing on a particular subject; it implies in-depth discussion. 
During the debate, the senator will discourse on healthcare reform.
Pro Tip 2/3Formal Context
'Discourse on' is formal and often used in academic or professional settings. 
The scientist's lecture will discourse on the ramifications of gene editing.
Pro Tip 3/3Extended Speech
The phrase indicates a long and thorough talk rather than a brief mention. 
The author's seminar will discourse on the cultural significance of mythology.