Best medicine: American Conservatory Theater presents “The Imaginary Invalid,” Molière’s comedy about 17th-century health care, told through the story of a tightwad hypochondriac. [8 p.m., A.C.T., 415 Geary St.]

Who’s in town

Broadway musical-theater performer Marin Mazzie, direct from her role as the Lady of the Lake in “Spamalot,” appears in “Yes, It’s Today,” a cabaret show celebrating the music of Jerry Herman and Kander and Ebb. [8 p.m., Empire Plush Room, York Hotel, 940 Sutter St.]

City activities

Mozart for lunch: The Midsummer Mozart Festival Ensemble performs compositions by Mozart. [12:30 p.m., St. Patrick’s Church, 756 Mission St.]

Day game: The Giants end their current home stand with a game against the Toronto Blue Jays. [12:35 p.m., AT&T Park, 24 Willie Mays Plaza]

At the public library

E-mail class: Instruction covers how to set up an account, compose messages and send and receive e-mail. [2 to 4 p.m., Mission Bay Branch, 960 Fourth St.]

Business counseling: The Service Corps of Retired Executives offers free sessions. [10 a.m. to 3 p.m., Main Library, Business Center, 100 Larkin St.; call (415) 744-6827 for an appointment]

Lectures

Eric Schmitt: The New York Times military correspondent discusses his trips to Iraq and Afghanistan and his series exposing the sale of sensitive U.S. technology to China. [12:30 p.m., Commonwealth Club, 595 Market St.]

William Ratliff: The scholar of Latin American history and international relations discusses Latin America’s current political landscape and leftist governments. [Noon, World Affairs Council, 312 Sutter St.]

Literary events

Michael Ondaatje: The author of “The English Patient” appears in conversation with poet Robert Hass. [8 p.m., Herbst Theatre, 401 Van Ness Ave.]

Martin Cruz Smith: The novelist discusses “Stalin’s Ghost.” [12:30 p.m., Stacey’s Bookstore, 581 Market St.]