His body was nothing but a boneless sac of mental effluent. Somewhere way away, he heard it moan and rock on the bed with a liquid gurgling.

Isaac reeled. Somewhere in the flickering onslaught of emotion and bathos he discerned a thin, constant stream of disgust and fear that he recognized as his own. He struggled towards it through the sludge of imagined and replayed dramas of consciousness. He touched the tentative dribble of nausea that was indisputably what he was feeling at that moment, held fast, centred himself in it…Isaac clung to it with radical fervour.

He held to his core, buffeted by the dreams around him. Isaac flew over a spiky town, a six-year-old girl laughing delightedly in a language he had never heard but momentarily understood as his own; he bucked with inexpert excitement as he dreamed the sex dream of a pubescent boy; he swam through estuaries and visited strange grottoes and fought ritualistic battles. He wandered through the flattened veldt of the daydreaming cactacae mind. Houses morphed around him with the dreamlogic that seemed to be shared by all the sentient races of Bas-Lag.

New Crobuzon appeared here and there, in its dream form, in its remembered or imagined geography, with details highlighted and others missing, great gaps between streets that were traversed in seconds.

There were other cities and countries and continents in these dreams. Some were doubtless dreamlands born behind flickering eyelids. Others seemed references: oneiric nods to solid places, cities and towns and villages as real as New Crobuzon, with architecture and argots that Isaac had not seen or heard.

The sea of dreams in which he swam, Isaac realized, contained drops from very far afield.

Less of a sea, he thought drunkenly from the bottom of his unstuck mind, and more of a consomme. He imagined himself chewing stolidly on the gristle and giblets of alien minds, lumps of rancid dream sustenance floating in a thin gruel of half-memories. Isaac retched mentally. I’ll throw up in here I’ll turn my head inside out, he thought.

The memories and dreams came in waves. Tides carried them in thematic washes. Even adrift in the wash of random thoughts, Isaac was carried across the vistas inside his head on recognizable currents. He succumbed to the tugging of money dreams, a trend of recollections of stivers and dollars and head of cattle and painted shells and promise-tablets.

He rolled in a surf of sex dreams: cactacae men ejaculating across the earth, across the rows of eggbulbs planted by the women; khepri women rubbing oil across each other in friendly orgies; celibate human priests dreaming out their guilty, illicit desires.

Isaac spiralled in a little whirlpool of anxiety dreams. A human girl about to enter her exams, he found himself walking nude to school; a vodyanoi watercraefter whose heart raced as stinging saline water poured back from the sea into his river; an actor who stood dumb on stage, unable to recall a single line of his speech.

My mind’s a cauldron, Isaac thought, and all these dreams are bubbling over.

The slop of ideas came quicker and thicker. Isaac thought of that and tried to latch onto the rhyme, focusing on it and investing it with portent, repeating it quicker and quicker and thicker and thicker and quicker, trying to ignore the barrage, the torrent, of psychic effluvia.

It was no use. The dreams were in Isaac’s mind, and there was no escape. He dreamed that he dreamed other people’s dreams, and realized that his dream was true.

All he could do was try, with a febrile, terrified intensity, to remember which of the dreams was his own.

There was a frantic chirruping coming from somewhere close by. It wound its way through a skein of the images that gusted through Isaac’s head, then grew in intensity until it ran through his mind as the dominant theme.

Abruptly, all the dreams stopped.

Isaac opened his eyes too quickly and swore with the pain that gushed into his head with the light. He reached his hand up and felt it lolling against his head like a big, vague paddle. He laid it heavily across his eyes.

The dreams had stopped. Isaac peeked through his fingers. It was day. It was light.

“By…Jabber’s…arse…” he whispered. The effort made his head ache.

This was absurd. He had no sense of time lost. He remembered everything clearly. If anything, his immediate recollection seemed heightened. He had a clear sense of having lolled and sweated and wailed under the influence of the dreamshit for about half an hour, no longer. And yet it was…he struggled with his eyelids, squinted at the clock…it was half past seven in the morning, hours and hours since he had fought his way onto the bed.

He propped himself on his elbows and examined himself. His dark skin was slick and grey. His mouth reeked. Isaac realized that he must have lain almost motionless for the whole night: the covers were a little rucked, that was all.

The terrified birdsong that had woken him started again. Isaac shook his head in irritation and looked for its source. A tiny bird circled desperately in the air around the inside of the warehouse. Isaac realized that it was one of the previous evening’s reluctant escapees, a wren, obviously afraid of something. As Isaac looked around to see what had the bird so nervous, the lithe reptilian body of an aspis flew like a crossbow bolt from one corner of the eaves to the other. It plucked the little bird from the air as it passed. The wren’s calls were cut short abruptly.

Isaac stumbled inexpertly out of bed and circled confusedly. “Notes,” he told himself. “Make notes.”

He snatched paper and pen from his desk and began to scribble down his recollections of the dreamshit.

“What the fuck was that?” he whispered out loud as he wrote. “Some cove’s doing a damn good job of reproducing the biochymistry of dreams, or tapping it at source…” He rubbed his head again. “Lord, what sort of thing is it that eats this…” Isaac stood briefly and glanced at his captive caterpillar.

He was quite still. His mouth gaped idiotically, then worked up and down and finally shaped words.

“Oh. My. Good. Arse.”

He stumbled slowly, nervously across the room, seeming to hang back, chary of seeing what he was seeing. He approached the cage.

Inside, a colossal mass of beautifully coloured grub-flesh wriggled unhappily. Isaac stood uneasily over the enormous thing. He could feel the odd little vibrations of alien unhappiness in the aether around him.

The caterpillar had at least tripled in size overnight. It was a foot long, and correspondingly fat. The faded magnificence of its coloured patches had returned to their initial, burnished brilliance. With interest. The sticky-looking hairs on its tail-end were wicked-looking bristles. It had no more than six inches of space around it on all sides. It nudged weakly against the sides of the hutch. “What happened to you?” hissed Isaac.

He recoiled and gazed at the thing, which waved its head in the air blindly. He thought quickly, pictured the number of dreamshit lozenges he had given the grub to eat. He looked around and saw the envelope containing all the remains where he had left it, untouched. The thing hadn’t got out and gorged itself. There was no way, Isaac realized, that the little pellets of drug he had left in that hutch contained anything like the number of calories that the caterpillar had used on growth over the night. Even if it had just piled on weight ounce for ounce with what it had eaten, it would not have represented an increase in this league.

“Whatever energy you’re getting out of your supper,” he whispered, “it’s not physical. What in Jabber’s name are you?”