Michael Ondaatje has always been a poet – it is how he began his career 50 years ago – although he is more famous as a novelist and especially for his 1992 Booker prize-winning The English Patient (which also won the Golden Man Booker in 2018). In A Year of Last Things, he is writing about last – and lost – things. He is not interested in the known quantity, has always been more at home with the unknown, and is extraordinarily attuned to hauntings, to the idea that missing pieces are likely to inform whatever remains. The opening poem, Lock, begins:

Reading the lines he loves
he slips them into a pocket,
wishes to die with his clothes
full of torn-free stanzas

In the cherishing of “torn-free stanzas” one recognises the romance of the incomplete.

Lock is followed by Definition, a generous poem where each word offers something new:

All afternoon I stroll the plotless thirteen hundred
pages of a Sanskrit dictionary
with its verbs for holy obsessions,
the name for an alcove
of coin washers whose fingers glint
all night with dark lead, grains of silver

The Sanskrit language becomes coinage and Ondaatje turns up gold. There is an exhilaration in the using of a dictionary not to find the word for something you already knew but to open the door on something you didn’t. Of Tamil, Sinhalese and Dutch descent, Ondaatje, who has lived for most of his life in Canada, has always been a traveller, but in this poem, language is his means of transport. Exoticism is underpinned by surprise, a revelling in joyous juxtaposition, in unexpected focusing – as on the person whose occupation might seem a novelty: “the census taker of birds”.

Ondaatje is a connoisseur – and creator – of atmospheres. This valedictory collection brims with rivers – rivers not so much like Lethe as ones that remember. At their best, his poems take you into an elsewhere, although his taste for the mysterious occasionally seems too much of a default position. Keats might have been right that unheard melodies are sweetest, but there are too many quick enigmas here: “the notes of an unknown bird” or “some unread letter, written long ago”, from Mask.

He has always been fascinated by maps (like the boy in his beautiful novel Warlight). This collection returns to maps – and maplessness. In The Geography Sixth, he writes about “dutiful maps of pilgrimages”. In Bruise, “the maps he relies on have worn out”. In The Great Impermanence: “In earlier centuries we were guided/ by few travel maps for the heart.”

How do we navigate the past? Photographs are considered in a manner recalling WG Sebald, and Ondaatje includes a benign poem on a lover’s past (a subject to which Julian Barnes devoted an entire jealous novel). In The Then, Ondaatje writes:

A strange awakening thought at 7am
to erase this life, and desire what I might have known
in photographs of you before we met

His poems about the loss of his dog and cat are wonderful too – dignified and unsentimental. We only learn Stella is a dog seven lines in, and the anecdotal then shifts gear with a quickening of grief in its final question.

But it is to the tremendous riddle A Bus to Fez that I keep returning. He describes a female companion on the bus and in life: “…her quiet/ hand on my sleeve warning me of a flame”. But is she altogether imagined as stated? She appears to be her own person and might be part of him or might be no one. She might be the love of his life.

Stella by Michael Ondaatje

This morning before daybreak a thunderstorm

In the last hours before her death
her enemies came. A raccoon, that storm,
the FedEx truck manned by a gentle woman
who’d recently lost her own dog.
Considering the woman who was usually her enemy
our dog perhaps read the grief in her,

just as, the night before, a raccoon
along the fence backlit by moonlight
watched our dog drink noisily from the fountain,
her thin body so thirsty! never sensing
the creature who continued
along the fence and disappeared

So many things to learn, keep on learning
during these last days, watching us
with an awareness that we perhaps
have not learned but shall

Now we are less. How do we become more?

How to die courteous and beautiful
protecting her house, guarding our door

• A Year of Last Things by Michael Ondaatje is published by Cape (£14.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply