Yoga Sutra 1.30 distractions of the mind are the obstacles
Sūtra I.30
Illness, apathy, doubt, carelessness, laziness, failure to withdraw, misconceptions, failure to attain a state, instability (in the state) – these distractions of the mind are the obstacles
There are nine obstacles which distract the mind. They appear only in conjunction with the mental processes described previously, and without the obstacles, the latter do not arise.
Illness is loss of balance in the humours (dhātu), secretions (rasa) or organs. Apathy is mental ineffectiveness. Doubt is an idea embracing both alternatives, in the form ‘This might be so, or it might not be so’. Carelessness is lack of devotion to the means to samādhi. Laziness is inertia from heaviness physical and mental. Failure to withdraw is a hankering caused by past addiction to objects. Misconceptions are illusory knowledge (viparyaya jñāna). Failure to attain a state is not attaining any stage of samādhi. Instability is when a state has been attained but the mind is not established in it. It is an obstacle because in true attainment of samādhi the mind would be established there.
These distractions are explained as the blemishes, adversaries and obstacles of yoga.
In number they are nine, and they consist of illness and the rest. Illness is loss of balance in the humours, secretions or organs. The humours are air, bile, and phlegm; when the harmony between them is lost they become out of balance, and this happens when there is habitual excess (of one or two of them). Medicine teaches that an increase of a humour may be spontaneous or caused by something else.
The secretions are particular transformations of the food eaten. They are of seven kinds, and they are called secretions (rasa) because they are effects of the food-essence (rasa). Technically they are named rasa, blood, fat, flesh, bone, marrow and semen (śukla) and they become out of balance when there is excess or loss.
Disorder of the organs is blindness, deafness, etc.
Apathy is mental ineffectiveness a sort of paralysis.
Doubt is an idea which touches two contradictory alternatives, for instance, ‘Is it a post or a man?’
Carelessness is lack of devotion to the means to samādhi a lack of persistence.
Laziness is inertia from heaviness physical and mental.
Failure to withdraw means either actual contact with the objects, or hankering the desire or thirst caused by past addiction.
Misconceptions are illusory knowledge deluded ideas about the yoga methods or the path itself.
Failure to attain a state not attaining any stage of samādhi; the stages such as vitarka have been mentioned as particular qualities of the mind, and will be discussed later (sūtra I.41–44).
Instability is when a stage of samādhi has been attained but it is unstable. Then by some means he should try to re-establish his unsteady mind in it. If this attempt is not successful, it is called instability.
These are the nine obstacles (antarāya). They are called antarāya because they move (āya) towards or create, an interval (antara), a gap, a break. They are known as the distractions, adversaries or blemishes in the achievement of yoga.
They appear only in conjunction with the processes of the mind described previously. They are distractions of mind because they distract it with various objects, and they appear only in conjunction with the processes of the mind of the five kinds, the two groups being reciprocally impelling and impelled. without the obstacles in the absence of illness and the other obstacles, the aforesaid mental processes like right knowledge do not arise, because there is no power to support them. As inevitably causing processes in the mind, the mental distractions are all classed as equally unfavourable.