WAR IS OVER if you want it

She is 80 years old.

Of course Ono is so much more, but coupled with the Yang to her Yin, John Lennon and Yoko Ono live on in my imagination as a couple with lots of hair, charisma and who epitomise the hope of youth in a cool, activist, peace movement 60's kind-of-way ... and I just can't believe this woman is an octogenarian!

I will now blaspheme.

The Beatles (John Lennon, Paul McCartney, George Harrison and Ringo Starr) were a talented group of performers and – though I am ignorant regarding any insightful knowledge of their work – they epitomised the zeitgeist of an era, or at least its soundtrack. They were a group of young men who definitely were in the right place, doing the right stuff at the right time.

As talented as the Beatles may have been, on John Lennon's meeting and forming both a personal and creative relationship with Yoko Ono, his professional profile evolved to that of fellow conceptual artist and political activist. While the remaining Beatles were definitely part of the emancipation euphoria of the time they did not appear to have the political commitment and vision of John Lennon and Yoko Ono.

OK ... so maybe Lennon and Ono's drugs were just a whole lot more transcendental, but Lennon and Ono shared a vision of obtainable world peace – a serious ambition that is light years beyond the realms of competitive commercial success.

WAR IS OVER if you want it sweeps you up in their creative, emotional and political partnership that began when Lennon walked into Ono's London exhibition at the Indica Gallery in 1966. This exhibition featured chess sets made with all white pieces – once the game begins you can not distinguish your opponent. It also was the exhibition that introduced Ono's instructional and participatory artworks to England. Apparently, it was from this first meeting that Lennon and Ono's extraordinary union began. Play it by Trust (the 2013 iteration of the work, realised for the MCA) presents multiple all white chess sets. Many couples were playing a little opponent-less chess at the time of my visit.

WAR IS OVER if you want it contains references through-out to Ono and Lennon's amazing relationship. Newspaper clippings and photographs referenced/captured the couple both in creative mode and as famous/infamous couple. That merging on different dimensions could be tragic, as in the blood red finger-prints on a pair of iconic little round glasses from FAMILY ALBUM (1993); warm, as in Yoko's Film No. 5 (Smile) (still) 1968 depicting John Lennon gazing quietly at the camera as his expression gradually transforms into a beatific smile; or cheeky, quite literally, as a line up of bare and (we are told) famous bottoms parade for Ono's camera. Undoubtedly Lennon's bottom would have made the grade in Film No. 4 (Bottoms) (1966-67).

As mentioned, central to Ono's work is an open-ended quality that invites her audience to participate and create their own meaning and significance. I was particularly moved by the lemon-scented eucalyptus saplings Ono has donated to the MCA Wish Tree for Sydney (1996/2013). Attached to their branches are messages written by the exhibition's visitors on little labels to mothers/mums/mamas/mommies. These leaves of emotion flutter in the Sydney Harbour breeze on the balcony of Level Four, MCA, while MY MOMMY IS BEAUTIFUL (2004/2013) is the MCA's mother-ship of an internal installation. I tied on my offerings amongst the other messages and reeled at the breadth of response that followed Ono's seemingly simple direction. I wrote to my beautiful mother that I missed her daily; apologised for any pain I had caused and forgave any pain she had caused. Others wrote similarly loving messages. Others still wrote with anger and despair .... Ono's seemingly simplistic interactive art works – this particular one very analogue and of this world with its focus on what would be the most archetypal of all relationships – blows away barriers and invites deeply intimate revelation.

I also enjoyed running my dampened finger over the silicone mould of a naked, female body touch me III (2008). I'm sure this work would resonate uniquely to whoever participates for I found this experience decidedly kinky, particularly when playing with the model's lips and nipples that felt so life-like! This piece was originally made as a response by Ono to the abuse so many women endure in their daily lives. I hope that in Sydney touch me III (2008) only receives tenderness.

You can take away a piece of blue sky from Ono's exhibition. You will select your bit of future peace from upturned military helmets that hang from the roof of the MCA in HELMETS –Pieces of Sky (2001/2013). I'd love to place a segment of Ono's conceptual collective sky next to a piece of the Berlin Wall. It would be a juxtaposition of past and possibility almost worthy of Yoko.

*The exhibition 'WAR IS OVER if you want it' takes its title from a 1969 campaign by Ono and her late husband, John Lennon, who rented public billboards in cities including London and New York over Christmas 1969 to spread their message of peace and hope for humankind.

A wonderful exhibition to visit over the festive period.