‘Anaesthetics (and the Way They Affect the Mind and Body)’ and ‘Stimulants (and the Way They Affect the Mind and Body)’ (1991) are amongst Hirst’s earliest ‘Natural History’ works. Whilst originally shown separately, the pieces conceptually relate to each other.
‘Anaesthetics’, one of Hirst’s first exhibited formaldehyde pieces, consists of two glass tanks filled solely with the solution. It was included in ‘Internal Affairs’ – his first solo show in a public gallery at the Institute of Contemporary Arts, London, in 1991. The work is an illustration of the conceptual importance of both glass and formaldehyde to Hirst’s work. The glass boxes repeatedly employed by the artist act to define the art work’s space, whilst simultaneously commenting on the “fragility of existence”. The glass, he describes as: “something dangerous and something to keep you away” – a material that you can see through despite its solidity.
The formaldehyde itself is used as much to communicate an idea as to preserve. The solution, extremely toxic despite its innocuous appearance, is associated with fear and memory, or the loss of it, for Hirst. He adds: “Sometimes I think you can create more of a kind of horror with empty water. A big empty tank of water is quite a frightening thing.”
‘Anaesthetics’ and ‘Stimulants’ explore minimalism and realism. Both subjects Hirst revisited in 1991 with ‘The Physical Impossibility of Death in the Mind of Someone Living’. They belong in Hirst's early series 'Internal Affairs' (many of which were exhibited at the 1991 ICA show of the same name.) Describing the series as a means of, ‘looking into myself, to try to work out why my body is separated from my mind or if indeed it is’, it contains some of Hirst’s most personal works. Unlike most of his other series, ‘Internal Affairs’ contains works made in a variety of mediums. As the artist explained in 1991: “I thought the ideas involved in ‘Internal Affairs’ needed to be realized in more than one sculpture. It had to be approached from different angles.” The series also includes the vitrine ‘The Acquired Inability to Escape’ (1991), and the ping-pong ball piece, ‘I Want to Spend the Rest of My Life Everywhere, with Everyone, One to One, Always, Forever, Now’ (1991).
 Damien Hirst cited in Damien Hirst and Gordon Burn, ‘On the Way to Work’ (Faber and Faber, 2001),124–125
 Damien Hirst cited in Damien Hirst, ‘I Want to Spend the Rest of My Life Everywhere, with Everyone, One to One, Always, Forever, Now’ (Booth-Clibborn Editions; Reduced edition, 2005), 33
 Damien Hirst cited in ‘Like People, Like Flies: Damien Hirst Interviewed’, Mirta D’Argenzio, ‘The Agony and the Ecstasy: Selected Works 1989–2004’ (Electa Napoli, 2004), 70
 Damien Hirst cited in Damien Hirst, ‘I Want to Spend the Rest of My Life Everywhere, with Everyone, One to One, Always, Forever, Now’, 286